From mboxrd@z Thu Jan 1 00:00:00 1970 From: Romain Naour Date: Sat, 8 Sep 2018 16:02:08 +0200 Subject: [Buildroot] [PATCH] SSP: disable ssp support on microblaze In-Reply-To: <20180701145522.3f8d670c@windsurf.home> References: <20180610163300.6440-1-romain.naour@gmail.com> <20180701145522.3f8d670c@windsurf.home> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Le 01/07/2018 ? 14:55, Thomas Petazzoni a ?crit?: > Hello, > > On Sun, 10 Jun 2018 18:33:00 +0200, Romain Naour wrote: >> As reported by [1], SSP support is missing in the Buildroot toolchain >> for microblaze even if it's requested by selecting >> BR2_TOOLCHAIN_HAS_SSP config option. >> >> In Buildroot, we are using libssp provided by the C library (Glibc, >> musl, uClibc-ng) when available. We are not using libssp from gcc. >> >> So for a microblaze glibc based toolchain, the SSP support is enabled >> unconditionally by a select BR2_TOOLCHAIN_HAS_SSP. >> >> BR2_microblazeel=y >> BR2_TOOLCHAIN_BUILDROOT_GLIBC=y >> BR2_KERNEL_HEADERS_4_14=y >> BR2_BINUTILS_VERSION_2_30_X=y >> BR2_GCC_VERSION_8_X=y >> BR2_TOOLCHAIN_BUILDROOT_CXX=y >> >> While building the toolchain, we are building host-binutils which >> provide "as" (assembler) and host-gcc-initial wich provide a >> minimal cross gcc (C only cross-compiler without any C library). >> When SSP support is requested, gcc_cv_libc_provides_ssp=yes is >> added to the make command line (see [2] for full details) >> >> With this setting, the SSP support is requested but it's not available >> in the end and the toochain build succeed. >> >> When the microblaze toolchain is imported to Biuldroot (2018.05) as >> external toolchain with BR2_TOOLCHAIN_EXTERNAL_HAS_SSP set, the build >> stop with : >> "SSP support not available in this toolchain, please disable BR2_TOOLCHAIN_EXTERNAL_HAS_SSP" >> >> The test is doing the following command line: >> >> echo 'void main(){}' | [...]/host/bin/microblazeel-linux-gcc.br_real -Werror -fstack-protector -x c - -o [...]/build/.br-toolchain-test.tmp >> cc1: error: -fstack-protector not supported for this target [-Werror] >> >> When we look at the gcc-final log file (config.log) we can see this >> error several time when using the minimal gcc (from host-gcc-initial). >> So Why the minimal gcc doesn't support SSP? >> >> When we look at the gcc-initial log file (config.log) we can see an >> error with 'as': >> >> configure:23194: checking assembler for cfi directives >> configure:23209: [...]microblazeel-buildroot-linux-gnu/bin/as -o conftest.o conftest.s >&5 >> conftest.s: Assembler messages: >> conftest.s:2: Error: CFI is not supported for this target >> conftest.s:3: Error: CFI is not supported for this target >> conftest.s:4: Error: CFI is not supported for this target >> conftest.s:5: Error: CFI is not supported for this target >> conftest.s:6: Error: CFI is not supported for this target >> conftest.s:7: Error: CFI is not supported for this target >> configure:23212: $? = 1 >> configure: failed program was >> .text >> .cfi_startproc >> .cfi_offset 0, 0 >> .cfi_same_value 1 >> .cfi_def_cfa 1, 2 >> .cfi_escape 1, 2, 3, 4, 5 >> .cfi_endproc >> >> This is the only relevant difference compared to a nios2 toolchain where >> libssp is enabled and available (nios2 is an example). >> >> "CFI" stand for "Control Flow Integrity" and it seems that SSP support >> requires CFI target support (see [3] for some explanation). >> >> The SSP support seems to depends on CFI support, but the toolchain >> infrastructure is not detailed enough to handle the CFI dependency. >> >> In the other hand, microblaze is the only architecture where CFI support >> is missing. >> >> Disable SSP support for microblaze entirely. >> >> Fixes: >> https://gitlab.com/free-electrons/toolchains-builder/-/jobs/72006389 >> >> [1] https://gitlab.com/free-electrons/toolchains-builder/issues/1 >> [2] https://git.buildroot.net/buildroot/tree/package/gcc/gcc.mk?h=2018.05#n275 >> [3] https://grsecurity.net/rap_faq.php >> >> Signed-off-by: Romain Naour >> Cc: Thomas Petazzoni > > Thanks for working on this. Based on this explanation, I think I'd > prefer to see something like this in package/binutils/Config.in.host > > config BR2_PACKAGE_HOST_BINUTILS_SUPPORTS_CFI > default y > depends on !BR2_microblaze The CFI support also depends on binutils version. For example, NiosII gained CFI support with binutils 2.30. The nios2--glibc--bleeding-edge-2017.05-toolchains-1-2.tar.bz2 toolchain is affected by this issue. You can't import it with Buildroot > 2018.02. Best regards, Romain > >> diff --git a/package/glibc/Config.in b/package/glibc/Config.in >> index 57a2e833d2..7adf76699d 100644 >> --- a/package/glibc/Config.in >> +++ b/package/glibc/Config.in >> @@ -4,6 +4,7 @@ config BR2_PACKAGE_GLIBC >> bool >> default y >> select BR2_PACKAGE_LINUX_HEADERS >> - select BR2_TOOLCHAIN_HAS_SSP >> + # SSP not supported on microblaze >> + select BR2_TOOLCHAIN_HAS_SSP if !BR2_microblaze > > select BR2_TOOLCHAIN_HAS_SSP if BR2_PACKAGE_HOST_BINUTILS_SUPPORTS_CFI > >> diff --git a/package/musl/Config.in b/package/musl/Config.in >> index bedc50cd45..4e0d6f4ef1 100644 >> --- a/package/musl/Config.in >> +++ b/package/musl/Config.in >> @@ -4,6 +4,7 @@ config BR2_PACKAGE_MUSL >> depends on BR2_TOOLCHAIN_USES_MUSL >> select BR2_PACKAGE_LINUX_HEADERS >> # SSP broken on i386/ppc: http://www.openwall.com/lists/musl/2016/12/04/2 >> - select BR2_TOOLCHAIN_HAS_SSP if !(BR2_i386 || BR2_powerpc) >> + # SSP not supported on microblaze >> + select BR2_TOOLCHAIN_HAS_SSP if !(BR2_i386 || BR2_microblaze || BR2_powerpc) > > select BR2_TOOLCHAIN_HAS_SSP if BR2_PACKAGE_HOST_BINUTILS_SUPPORTS_CFI && !(BR2_i386 || BR2_powerpc) > >> config BR2_TOOLCHAIN_BUILDROOT_USE_SSP >> bool "Enable stack protection support" >> + depends on !BR2_microblaze # SSP not supported on microblaze > > depends on BR2_PACKAGE_HOST_BINUTILS_SUPPORTS_CFI > >> select BR2_TOOLCHAIN_HAS_SSP >> help >> Enable stack smashing protection support using GCCs >> diff --git a/toolchain/Config.in b/toolchain/Config.in >> index 3a53a32a6d..1bf71a6d52 100644 >> --- a/toolchain/Config.in >> +++ b/toolchain/Config.in >> @@ -122,6 +122,9 @@ config BR2_TOOLCHAIN_HAS_THREADS_NPTL >> >> config BR2_TOOLCHAIN_HAS_SSP >> bool >> + # SSP support require CFI architecture support. >> + # https://gitlab.com/free-electrons/toolchains-builder/issues/1 >> + depends on !BR2_microblaze # missing CFI support in "gas" > > And this change is not necessary. Really BR2_TOOLCHAIN_HAS_SSP > is a blind option that indicates if the toolchain has SSP support or > not, it's not meant to handle the dependencies of SSP. support. > > Could you rework your patch accordingly if you agree with the proposal ? > > Thanks! > > Thomas >