From patchwork Sat Feb 20 15:04:13 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nix X-Patchwork-Id: 10970 Received: (qmail 77571 invoked by alias); 20 Feb 2016 15:04:25 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 77557 invoked by uid 89); 20 Feb 2016 15:04:25 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=1.8 required=5.0 tests=BAYES_50, KAM_LAZY_DOMAIN_SECURITY, UNPARSEABLE_RELAY autolearn=no version=3.3.2 spammy=differentiate, xno, 6026, sk:arbitra X-HELO: userp1040.oracle.com From: Nix To: Andreas Schwab Cc: libc-alpha@sourceware.org, carlos@redhat.com Subject: Re: [PATCH 01/12] Configury support for --enable-stack-protector. References: <1455963826-21885-1-git-send-email-nix@esperi.org.uk> <1455963826-21885-2-git-send-email-nix@esperi.org.uk> Date: Sat, 20 Feb 2016 15:04:13 +0000 In-Reply-To: (Andreas Schwab's message of "Sat, 20 Feb 2016 11:44:29 +0100") Message-ID: <87lh6fo236.fsf@esperi.org.uk> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) MIME-Version: 1.0 On 20 Feb 2016, Andreas Schwab outgrape: > Nix writes: > >> +AC_ARG_ENABLE([stack-protector], >> + AC_HELP_STRING([--enable-stack-protector=@<:@yes|no|all|strong@:>@], >> + [Detect stack overflows in glibc functions with large string buffers, or in all glibc functions]), > > Please explain the meaning of the argument in the help string. OK, so this is a bit long in the output: --enable-stack-protector=[yes|no|all|strong] Detect stack overflows in glibc functions, either with local buffers (yes), or with those plus arrays (strong), or all functions (all) but it does what you asked for, I think. Adjusted patch below. (The line in configure.ac is rather long, but I don't think that line is breakable easily.) ---------------- >8 ---------------- From: Nick Alcock Date: Fri, 19 Feb 2016 17:25:05 +0000 Subject: [PATCH] Configury support for --enable-stack-protector. This adds =all and =strong, with obvious semantics, and with a rather arbitrarily-chosen default off, which we might well want to change to something stronger once this patch has been tested by people other than me. We don't validate the value of the option yet: that's in a later patch. Nor do we use it for anything at this stage. We differentiate between 'the compiler understands -fstack-protector' and 'the user wanted -fstack-protector' so that we can pass -fno-stack-protector in appropriate places even if the user didn't want to turn on -fstack-protector for other parts. (This helps us overcome another existing limitation, that glibc doesn't work with GCC's hacked to pass in -fstack-protector by default.) We might want to add another configuration option to turn on -fstack-protector for nscd and other network-facing operations by default, but for now I've stuck with one option to control everything. --- configure.ac | 61 ++++++++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 41 insertions(+), 20 deletions(-) diff --git a/configure.ac b/configure.ac index 3c766b7..61bf882 100644 --- a/configure.ac +++ b/configure.ac @@ -232,6 +232,18 @@ AC_ARG_ENABLE([bind-now], [bindnow=no]) AC_SUBST(bindnow) +dnl Build glibc with -fstack-protector, -fstack-protector-all, or +dnl -fstack-protector-strong. +AC_ARG_ENABLE([stack-protector], + AC_HELP_STRING([--enable-stack-protector=@<:@yes|no|all|strong@:>@], + [Detect stack overflows in glibc functions, either with local buffers (yes), or with those plus arrays (strong), or all functions (all)]), + [enable_stack_protector=$enableval], + [enable_stack_protector=no]) +case x"$enable_stack_protector" in + xall|xyes|xno|xstrong) ;; + *) AC_MSG_ERROR([Not a valid argument for --enable-stack-protector]);; +esac + dnl On some platforms we cannot use dynamic loading. We must provide dnl static NSS modules. AC_ARG_ENABLE([static-nss], @@ -602,6 +614,35 @@ fi test -n "$base_machine" || base_machine=$machine AC_SUBST(base_machine) +AC_CACHE_CHECK(for -fstack-protector, libc_cv_ssp, [dnl +LIBC_TRY_CC_OPTION([$CFLAGS $CPPFLAGS -Werror -fstack-protector], + [libc_cv_ssp=yes], + [libc_cv_ssp=no]) +]) + +AC_CACHE_CHECK(for -fstack-protector-strong, libc_cv_ssp_strong, [dnl +LIBC_TRY_CC_OPTION([$CFLAGS $CPPFLAGS -Werror -fstack-protector-strong], + [libc_cv_ssp_strong=yes], + [libc_cv_ssp_strong=no]) +]) + +AC_CACHE_CHECK(for -fstack-protector-all, libc_cv_ssp_all, [dnl +LIBC_TRY_CC_OPTION([$CFLAGS $CPPFLAGS -Werror -fstack-protector-all], + [libc_cv_ssp_all=yes], + [libc_cv_ssp_all=no]) +]) + +stack_protector= +if test x$enable_stack_protector = xyes && test $libc_cv_ssp = yes; then + stack_protector=-fstack-protector +elif test x$enable_stack_protector = xall && test $libc_cv_ssp_all = yes; then + stack_protector=-fstack-protector-all +elif test x$enable_stack_protector = xstrong && test $libc_cv_ssp_strong = yes; then + stack_protector=-fstack-protector-strong +fi +AC_SUBST(libc_cv_ssp) +AC_SUBST(stack_protector) + # For the multi-arch option we need support in the assembler & linker. AC_CACHE_CHECK([for assembler and linker STT_GNU_IFUNC support], libc_cv_ld_gnu_indirect_function, [dnl @@ -1389,26 +1430,6 @@ else fi AC_SUBST(fno_unit_at_a_time) -AC_CACHE_CHECK(for -fstack-protector, libc_cv_ssp, [dnl -LIBC_TRY_CC_OPTION([$CFLAGS $CPPFLAGS -Werror -fstack-protector], - [libc_cv_ssp=yes], - [libc_cv_ssp=no]) -]) - -AC_CACHE_CHECK(for -fstack-protector-strong, libc_cv_ssp_strong, [dnl -LIBC_TRY_CC_OPTION([$CFLAGS $CPPFLAGS -Werror -fstack-protector-strong], - [libc_cv_ssp_strong=yes], - [libc_cv_ssp_strong=no]) -]) - -stack_protector= -if test "$libc_cv_ssp_strong" = "yes"; then - stack_protector="-fstack-protector-strong" -elif test "$libc_cv_ssp" = "yes"; then - stack_protector="-fstack-protector" -fi -AC_SUBST(stack_protector) - AC_CACHE_CHECK(whether cc puts quotes around section names, libc_cv_have_section_quotes, [cat > conftest.c <