From patchwork Mon Nov 28 12:32:19 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nix X-Patchwork-Id: 17989 Received: (qmail 49564 invoked by alias); 28 Nov 2016 12:33:16 -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 49420 invoked by uid 89); 28 Nov 2016 12:33:14 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.4 required=5.0 tests=AWL, BAYES_00, KAM_LAZY_DOMAIN_SECURITY, RP_MATCHES_RCVD autolearn=ham version=3.3.2 spammy=H*Ad:D*oracle.com, earliest, sk:statica, UD:op X-HELO: mail.esperi.org.uk From: Nix To: libc-alpha@sourceware.org Cc: fweimer@redhat.com, Nick Alcock Subject: [PATCH 03/12] Mark all machinery needed in early static-link init as -fno-stack-protector. Date: Mon, 28 Nov 2016 12:32:19 +0000 Message-Id: <20161128123228.30856-4-nix@esperi.org.uk> In-Reply-To: <20161128123228.30856-1-nix@esperi.org.uk> References: <20161128123228.30856-1-nix@esperi.org.uk> X-DCC--Metrics: spindle 1282; Body=3 Fuz1=3 Fuz2=3 From: Nick Alcock The startup code in csu/, brk() and sbrk(), and the __pthread_initialize_tcb_internal() function we just introduced are needed very early in initialization of a statically-linked program, before the stack guard is initialized; TLS initialization also uses memcpy(), which cannot overrun its own stack. Mark all of these as -fno-stack-protector. We also finally introduce @libc_cv_ssp@ and @no_stack_protector@, both substituted by the configury changes made earlier, to detect the case when -fno-stack-protector is supported by the compiler, and unconditionally pass it in when this is the case, whether or not --enable-stack-protector is passed to configure. (This means that it'll even work when the compiler's been hacked to pass -fstack-protector by default, unless the hackage is so broken that it does so in a way that is impossible to override.) (At one point we marked __libc_fatal() as non-stack-protected too, but this was pointless: all it did was call other routines which *are* stack-protected. The earliest __libc_fatal() call is in the DL_SYSDEP_OSCHECK hook on some platforms, when statically linking: this is fine, since it is after TLS and stack-canary initialization. I have tested invocation of programs statically and dynamically linked against this glibc on older kernels on x86 and ARM, and they still "work", i.e. fail with the appropriate message.) v2: No longer mark memcpy() as -fno-stack-protector. v3: Use $(no-stack-protector). v4: Use inhibit_stack_protector rather than de-protecting all of nptl-init.c. v5: Don't stack-protect brk() and sbrk() in the shared library. v7: Add comment in misc/Makefile. Commit message tweak. v8: Mark memcpy() as -fstack-protector again, along with wordcpy. * config.make.in (have-ssp): New. (no-stack-protector): New. * csu/Makefile (CFLAGS-.o): Use it. (CFLAGS-.og): Likewise. (CFLAGS-.op): Likewise. (CFLAGS-.os): Likewise. * misc/Makefile (CFLAGS-sbrk.o): Likewise. (CFLAGS-sbrk.op): Likewise. (CFLAGS-sbrk.og): Likewise. (CFLAGS-brk.o): Likewise. (CFLAGS-brk.op): Likewise. (CFLAGS-brk.og): Likewise. * string/Makefile (CFLAGS-memcpy.c): Likewise. (CFLAGS-wordcopy.c): Likewise. * nptl/nptl-init.c [!SHARED] (__pthread_initialize_tcb_internal): Likewise. --- config.make.in | 2 ++ csu/Makefile | 5 +++++ misc/Makefile | 9 +++++++++ nptl/nptl-init.c | 1 + string/Makefile | 4 ++++ 5 files changed, 21 insertions(+) diff --git a/config.make.in b/config.make.in index 04a8b3e..bfc7d39 100644 --- a/config.make.in +++ b/config.make.in @@ -58,7 +58,9 @@ with-fp = @with_fp@ enable-timezone-tools = @enable_timezone_tools@ unwind-find-fde = @libc_cv_gcc_unwind_find_fde@ have-fpie = @libc_cv_fpie@ +have-ssp = @libc_cv_ssp@ stack-protector = @stack_protector@ +no-stack-protector = @no_stack_protector@ have-selinux = @have_selinux@ have-libaudit = @have_libaudit@ have-libcap = @have_libcap@ diff --git a/csu/Makefile b/csu/Makefile index 31e8bb9..22afe67 100644 --- a/csu/Makefile +++ b/csu/Makefile @@ -45,6 +45,11 @@ before-compile += $(objpfx)version-info.h tests := tst-empty tst-atomic tst-atomic-long tests-static := tst-empty +CFLAGS-.o += $(no-stack-protector) +CFLAGS-.og += $(no-stack-protector) +CFLAGS-.op += $(no-stack-protector) +CFLAGS-.os += $(no-stack-protector) + ifeq (yes,$(build-shared)) extra-objs += S$(start-installed-name) gmon-start.os ifneq ($(start-installed-name),$(static-start-installed-name)) diff --git a/misc/Makefile b/misc/Makefile index 3d2ebb8..c382f92 100644 --- a/misc/Makefile +++ b/misc/Makefile @@ -105,6 +105,15 @@ CFLAGS-getusershell.c = -fexceptions CFLAGS-err.c = -fexceptions CFLAGS-tst-tsearch.c = $(stack-align-test-flags) +# Called during static library initialization, so turn stack-protection +# off for non-shared builds. +CFLAGS-sbrk.o = $(no-stack-protector) +CFLAGS-sbrk.op = $(no-stack-protector) +CFLAGS-sbrk.og = $(no-stack-protector) +CFLAGS-brk.o = $(no-stack-protector) +CFLAGS-brk.op = $(no-stack-protector) +CFLAGS-brk.og = $(no-stack-protector) + include ../Rules $(objpfx)libg.a: $(dep-dummy-lib); $(make-dummy-lib) diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c index dea335d..3288a85 100644 --- a/nptl/nptl-init.c +++ b/nptl/nptl-init.c @@ -287,6 +287,7 @@ static bool __nptl_initial_report_events __attribute_used__; #ifndef SHARED void +inhibit_stack_protector __pthread_initialize_tcb_internal (void) { /* Unlike in the dynamically linked case the dynamic linker has not diff --git a/string/Makefile b/string/Makefile index 69d3f80..3e35dca 100644 --- a/string/Makefile +++ b/string/Makefile @@ -71,6 +71,10 @@ CFLAGS-stratcliff.c = -fno-builtin CFLAGS-test-ffs.c = -fno-builtin CFLAGS-tst-inlcall.c = -fno-builtin +# Called during TLS initialization. +CFLAGS-memcpy.c = $(no-stack-protector) +CFLAGS-wordcopy.c = $(no-stack-protector) + ifeq ($(run-built-tests),yes) $(objpfx)tst-svc-cmp.out: tst-svc.expect $(objpfx)tst-svc.out cmp $^ > $@; \