[OpenWrt-Devel] [PATCH v2] toolchain: remove gcc libssp and use libc variant

[Ian Cooper]

Removes the standalone implementation of stack smashing protection
in gcc's libssp in favour of the native implementation in musl,
glibc and uClibc and introduces a uniform configuration interface.

This also makes kernel-level stack smashing protection available
for builds using non-musl libc (subject to architecture support).

Signed-off-by: Ian Cooper <iancooper at hotmail.com>
---

Update fixes an artefact with menuconfig which caused a toolchain
menu option to move to the front page of menuconfig due to the
removal of a prompt associated with a different CONFIG_ variable.

NOTE: after applying this patch you must do a make dirclean as the
entire toolchain and all packages will need to be rebuilt.

This patch does not change the behaviour ot the musl toolchain.
There are no changes to the uclibc toolchain since it's already
being compiled with it's native ssp implementation enabled.

 config/Config-build.in    | 4 ----
 toolchain/Config.in       | 6 +++++-
 toolchain/gcc/Config.in   | 8 --------
 toolchain/glibc/common.mk | 3 ++-
 4 files changed, 7 insertions(+), 14 deletions(-)

diff --git a/config/Config-build.in b/config/Config-build.in
index 61a9265ad7..ac1e05d2ff 100644
--- a/config/Config-build.in
+++ b/config/Config-build.in
@@ -249,7 +249,6 @@ menu "Global build settings"
 
 	choice
 		prompt "User space Stack-Smashing Protection"
-		depends on USE_MUSL
 		default PKG_CC_STACKPROTECTOR_REGULAR
 		help
 		  Enable GCC Stack Smashing Protection (SSP) for userspace applications
@@ -257,18 +256,15 @@ menu "Global build settings"
 			bool "None"
 		config PKG_CC_STACKPROTECTOR_REGULAR
 			bool "Regular"
-			select GCC_LIBSSP if !USE_MUSL
 			depends on KERNEL_CC_STACKPROTECTOR_REGULAR
 		config PKG_CC_STACKPROTECTOR_STRONG
 			bool "Strong"
-			select GCC_LIBSSP if !USE_MUSL
 			depends on KERNEL_CC_STACKPROTECTOR_STRONG
 	endchoice
 
 	choice
 		prompt "Kernel space Stack-Smashing Protection"
 		default KERNEL_CC_STACKPROTECTOR_REGULAR
-		depends on USE_MUSL || !(x86_64 || i386)
 		help
 		  Enable GCC Stack-Smashing Protection (SSP) for the kernel
 		config KERNEL_CC_STACKPROTECTOR_NONE
diff --git a/toolchain/Config.in b/toolchain/Config.in
index 762f4e10d7..e2af1c2c8e 100644
--- a/toolchain/Config.in
+++ b/toolchain/Config.in
@@ -283,8 +283,12 @@ config USE_MUSL
 	default y if !TOOLCHAINOPTS && !EXTERNAL_TOOLCHAIN && !NATIVE_TOOLCHAIN && !(arc)
 	bool
 
+config GCC_LIBSSP
+        default n
+        bool
+
 config SSP_SUPPORT
-	default y if USE_MUSL || GCC_LIBSSP
+	default y if !PKG_CC_STACKPROTECTOR_NONE
 	bool
 
 config USE_EXTERNAL_LIBC
diff --git a/toolchain/gcc/Config.in b/toolchain/gcc/Config.in
index 7d7f34210a..4b2ba7aaae 100644
--- a/toolchain/gcc/Config.in
+++ b/toolchain/gcc/Config.in
@@ -47,14 +47,6 @@ config GCC_DEFAULT_SSP
 	help
 	    Use gcc configure option --enable-default-ssp to turn on -fstack-protector-strong by default.
 
-config GCC_LIBSSP
-	bool
-	prompt "Build gcc libssp" if TOOLCHAINOPTS
-	depends on !USE_MUSL
-	default y if !USE_MUSL
-	help
-	    Enable Stack-Smashing Protection support
-
 config SJLJ_EXCEPTIONS
 	bool
 	prompt "Use setjump()/longjump() exceptions" if TOOLCHAINOPTS
diff --git a/toolchain/glibc/common.mk b/toolchain/glibc/common.mk
index db4f0fcc0e..f0b95d3cc7 100644
--- a/toolchain/glibc/common.mk
+++ b/toolchain/glibc/common.mk
@@ -39,7 +39,6 @@ ifeq ($(ARCH),mips64)
   endif
 endif
 
-
 # -Os miscompiles w. 2.24 gcc5/gcc6
 # only -O2 tested by upstream changeset
 # "Optimize i386 syscall inlining for GCC 5"
@@ -61,6 +60,8 @@ GLIBC_CONFIGURE:= \
 		--without-cvs \
 		--enable-add-ons \
 		--$(if $(CONFIG_SOFT_FLOAT),without,with)-fp \
+		  $(if $(CONFIG_PKG_CC_STACKPROTECTOR_REGULAR),--enable-stack-protector=yes) \
+		  $(if $(CONFIG_PKG_CC_STACKPROTECTOR_STRONG),--enable-stack-protector=strong) \
 		--enable-kernel=4.14.0
 
 export libc_cv_ssp=no
-- 
2.25.1


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