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Date: Mon, 2 Oct 2017 12:20:06 -0700
From: Kees Cook <keescook@...omium.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Kees Cook <keescook@...omium.org>,
Masahiro Yamada <yamada.masahiro@...ionext.com>,
Michal Marek <mmarek@...e.com>,
Ingo Molnar <mingo@...nel.org>,
Laura Abbott <labbott@...hat.com>,
Nicholas Piggin <npiggin@...il.com>,
Al Viro <viro@...iv.linux.org.uk>,
linux-kbuild@...r.kernel.org,
Yoshinori Sato <ysato@...rs.sourceforge.jp>,
Rich Felker <dalias@...c.org>,
"David S. Miller" <davem@...emloft.net>,
linux-kernel@...r.kernel.org,
linux-sh@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [PATCH 2/3] Makefile: Move stackprotector availability out of Kconfig
Various portions of the kernel, especially per-architecture pieces,
need to know if the compiler is building it 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@...ionext.com>
Cc: Michal Marek <mmarek@...e.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Laura Abbott <labbott@...hat.com>
Cc: Nicholas Piggin <npiggin@...il.com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: linux-kbuild@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
---
Makefile | 7 +++++--
arch/Kconfig | 8 --------
2 files changed, 5 insertions(+), 10 deletions(-)
diff --git a/Makefile b/Makefile
index d1119941261c..e122a9cf0399 100644
--- a/Makefile
+++ b/Makefile
@@ -688,8 +688,11 @@ else
stackp-flag := $(call cc-option, -fno-stack-protector)
endif
endif
-# Find arch-specific stack protector compiler sanity-checking script.
-ifdef CONFIG_CC_STACKPROTECTOR
+ifdef stackp-name
+ # If the stack protector has been selected, inform the rest of the build.
+ KBUILD_CFLAGS += -DCONFIG_CC_STACKPROTECTOR
+ KBUILD_AFLAGS += -DCONFIG_CC_STACKPROTECTOR
+ # Find arch-specific stack protector compiler sanity-checking script.
stackp-path := $(srctree)/scripts/gcc-$(SRCARCH)_$(BITS)-has-stack-protector.sh
stackp-check := $(wildcard $(stackp-path))
endif
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:
--
2.7.4
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