From patchwork Sun Mar 13 15:16:49 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nix X-Patchwork-Id: 11331 Received: (qmail 60507 invoked by alias); 13 Mar 2016 15:20:03 -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 60494 invoked by uid 89); 13 Mar 2016 15:20:02 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=1.4 required=5.0 tests=AWL, BAYES_50, KAM_LAZY_DOMAIN_SECURITY, RP_MATCHES_RCVD autolearn=no version=3.3.2 spammy=sk:static, 996, hacked, csu X-HELO: mail.esperi.org.uk From: Nix To: libc-alpha@sourceware.org Subject: [PATCH 04/17 v5] Mark all machinery needed in early static-link init as -fno-stack-protector. Date: Sun, 13 Mar 2016 15:16:49 +0000 Message-Id: <1457882222-22599-5-git-send-email-nix@esperi.org.uk> In-Reply-To: <1457882222-22599-1-git-send-email-nix@esperi.org.uk> References: <1457882222-22599-1-git-send-email-nix@esperi.org.uk> X-DCC-wuwien-Metrics: spindle 1290; Body=1 Fuz1=1 Fuz2=1 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. 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. * 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. * nptl/nptl-init.c [!SHARED] (__pthread_initialize_tcb_internal): Likewise. --- config.make.in | 2 ++ csu/Makefile | 5 +++++ misc/Makefile | 8 ++++++++ nptl/nptl-init.c | 1 + 4 files changed, 16 insertions(+) diff --git a/config.make.in b/config.make.in index 05ed6ec..9afd4ff 100644 --- a/config.make.in +++ b/config.make.in @@ -55,7 +55,9 @@ 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 d7bbc85..e3062f8 100644 --- a/misc/Makefile +++ b/misc/Makefile @@ -99,6 +99,14 @@ CFLAGS-getusershell.c = -fexceptions CFLAGS-err.c = -fexceptions CFLAGS-tst-tsearch.c = $(stack-align-test-flags) +# Called during static library initialization. +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 a4626be..2775d14 100644 --- a/nptl/nptl-init.c +++ b/nptl/nptl-init.c @@ -298,6 +298,7 @@ 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