linux-kernel - [PATCH 2/3] Makefile: Move stackprotector availability out of Kconfig

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1506972007-80614-3-git-send-email-keescook@chromium.org>
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