Various portions of the kernel, especially per-architecture pieces,
need to know if the compiler is building with the stack protector.
This was done in the arch/Kconfig with 'select', but this doesn't
allow a way to do auto-detected compiler support. In preparation for
creating an on-if-available default, move the logic for the definition of
CONFIG_CC_STACKPROTECTOR into the Makefile.
Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: linux-kbuild@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
Makefile | 6 +++++-
arch/Kconfig | 8 --------
arch/x86/Kconfig | 2 +-
3 files changed, 6 insertions(+), 10 deletions(-)
diff --git a/Makefile b/Makefile
index caa3f7e6f524..b486c0271866 100644
--- a/Makefile
+++ b/Makefile
@@ -689,7 +689,7 @@ else
endif
endif
# Find arch-specific stack protector compiler sanity-checking script.
-ifdef CONFIG_CC_STACKPROTECTOR
+ifdef stackp-name
stackp-path := $(srctree)/scripts/gcc-$(SRCARCH)_$(BITS)-has-stack-protector.sh
stackp-check := $(wildcard $(stackp-path))
# If the wildcard test matches a test script, run it to check functionality.
@@ -698,6 +698,10 @@ ifdef CONFIG_CC_STACKPROTECTOR
stackp-broken := y
endif
endif
+ ifndef stackp-broken
+ # If the stack protector is functional, enable code that depends on it.
+ KBUILD_CPPFLAGS += -DCONFIG_CC_STACKPROTECTOR
+ endif
endif
KBUILD_CFLAGS += $(stackp-flag)
diff --git a/arch/Kconfig b/arch/Kconfig
index 1aafb4efbb51..7007c1bfa79c 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -523,12 +523,6 @@ config HAVE_CC_STACKPROTECTOR
- its compiler supports the -fstack-protector option
- it has implemented a stack canary (e.g. __stack_chk_guard)
-config CC_STACKPROTECTOR
- def_bool n
- help
- Set when a stack-protector mode is enabled, so that the build
- can enable kernel-side support for the GCC feature.
-
choice
prompt "Stack Protector buffer overflow detection"
depends on HAVE_CC_STACKPROTECTOR
@@ -549,7 +543,6 @@ config CC_STACKPROTECTOR_NONE
config CC_STACKPROTECTOR_REGULAR
bool "Regular"
- select CC_STACKPROTECTOR
help
Functions will have the stack-protector canary logic added if they
have an 8-byte or larger character array on the stack.
@@ -563,7 +556,6 @@ config CC_STACKPROTECTOR_REGULAR
config CC_STACKPROTECTOR_STRONG
bool "Strong"
- select CC_STACKPROTECTOR
help
Functions will have the stack-protector canary logic added in any
of the following conditions:
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 971feac13506..8d3847071707 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -319,7 +319,7 @@ config X86_64_SMP
config X86_32_LAZY_GS
def_bool y
- depends on X86_32 && !CC_STACKPROTECTOR
+ depends on X86_32 && CC_STACKPROTECTOR_NONE
config ARCH_SUPPORTS_UPROBES
def_bool y
--
2.7.4
--
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