From mboxrd@z Thu Jan 1 00:00:00 1970 From: Romain Naour Date: Sat, 8 Sep 2018 15:17:07 +0200 Subject: [Buildroot] [PATCH] SSP: disable ssp support on microblaze In-Reply-To: <20180907092607.027fc274@windsurf.home> References: <20180610163300.6440-1-romain.naour@gmail.com> <20180701145522.3f8d670c@windsurf.home> <20180907092607.027fc274@windsurf.home> Message-ID: <8383696d-1a5f-03fe-befc-1e65c59f5582@gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Hi Thomas, Le 07/09/2018 ? 09:26, Thomas Petazzoni a ?crit?: > Romain, > > I was wondering if you had the chance to work on this topic ? Thanks for the reminder. I'll take a look. Best regards, Romain > > Thanks, > > Thomas > > On Sun, 1 Jul 2018 14:55:22 +0200, Thomas Petazzoni wrote: >> 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 >> >>> 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 > > >