From patchwork Sun Oct 10 16:38:33 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vivek Dasmohapatra X-Patchwork-Id: 46045 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id BDFE6385803B for ; Sun, 10 Oct 2021 16:42:44 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org BDFE6385803B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1633884164; bh=lYSsuW3c7qHVfGnT6a6d7884nRWLqBEqjX6uHTmKTCA=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=YH7jv1rBagwpiAOB4waHFRfUxjzJALtpNn/4WP5Y6zmPUx2CjPs+naD3Q7ZrlyMDh me4pKqhSKJjiiXaAlXlMnbCkxoGpe1ORxTxVS8CARVgxhk/8dLF5T3gXkyC3AJp78R Kg/S3BAcrnaJy+tE7512wLMoAXKEnBbjgrCI5Yp4= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [46.235.227.227]) by sourceware.org (Postfix) with ESMTPS id D9D273858404 for ; Sun, 10 Oct 2021 16:38:46 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org D9D273858404 Received: from noise.cbg.collabora.co.uk (unknown [IPv6:2001:4d48:ad5c:ef00:8e70:5aff:fe59:c29c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: vivek) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id DD8791F42E82 for ; Sun, 10 Oct 2021 17:38:45 +0100 (BST) To: libc-alpha@sourceware.org Subject: [PATCH v14 4/7] Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (bug 22745) Date: Sun, 10 Oct 2021 17:38:33 +0100 Message-Id: <20211010163836.14666-5-vivek@collabora.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20211010163836.14666-1-vivek@collabora.com> References: <20211010163836.14666-1-vivek@collabora.com> MIME-Version: 1.0 X-Spam-Status: No, score=-12.1 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, SPF_HELO_PASS, SPF_PASS, TXREP, URIBL_BLACK autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: =?utf-8?q?Vivek_Das=C2=A0Mohapatra_via_Libc-alpha?= From: Vivek Dasmohapatra Reply-To: =?utf-8?q?Vivek_Das=C2=A0Mohapatra?= Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" libc.so and other core DSOs should have the new unique-dso-by-default flag set to allow dlmopen to work better (libc et al instance shared by default when DSOs dlmopened into a new namespace). The following extra-libs have been merged into libc proper and do not require the new flag, since they are nly stubs now: nptl/libpthread htl/libpthread dlfcn/libdl login/libutil resolv/libanl --- Makeconfig | 3 +++ Makerules | 18 +++++++++++++- configure | 50 ++++++++++++++++++++++++++++++++++++--- configure.ac | 24 ++++++++++++++++--- dlfcn/Makefile | 1 + elf/Makefile | 3 +++ elf/dynamic-notes.c | 4 ++++ extra-lib.mk | 31 ++++++++++++++++++++++++ htl/Makefile | 2 ++ iconvdata/Makefile | 3 +++ iconvdata/extra-module.mk | 4 ++++ login/Makefile | 1 + nptl/Makefile | 5 +++- resolv/Makefile | 2 ++ 14 files changed, 143 insertions(+), 8 deletions(-) create mode 100644 elf/dynamic-notes.c diff --git a/Makeconfig b/Makeconfig index 2fa0884b4e..fc6af7a363 100644 --- a/Makeconfig +++ b/Makeconfig @@ -398,6 +398,9 @@ LDFLAGS-lib.so += -Wl,-z,now # Extra flags for dynamically linked non-test main programs. link-extra-flags += -Wl,-z,now endif +ifeq ($(ld_zunique),yes) +LDFLAGS-lib.so += -Wl,-z,unique +endif # Command to run after every final link (executable or shared object). # This is invoked with $(call after-link,...), so it should operate on diff --git a/Makerules b/Makerules index 596fa68376..830461ae1a 100644 --- a/Makerules +++ b/Makerules @@ -581,7 +581,8 @@ $(common-objpfx)shlib.lds: $(common-objpfx)config.make $(..)Makerules PROVIDE(__start___libc_IO_vtables = .);\ __libc_IO_vtables : { *(__libc_IO_vtables) }\ PROVIDE(__stop___libc_IO_vtables = .);\ - /DISCARD/ : { *(.gnu.glibc-stub.*) }@' + /DISCARD/ : { *(.gnu.glibc-stub.*) }@' \ + -e 's/^.*\*(\.dynamic).*$$/ .dynamic : { *dynamic-notes.os(.dynamic) *(.dynamic) }/' test -s $@T mv -f $@T $@ common-generated += shlib.lds @@ -636,6 +637,16 @@ build-shlib-objlist = $(build-module-helper-objlist) \ # Also omits crti.o and crtn.o, which we do not want # since we define our own `.init' section specially. LDFLAGS-c.so = -nostdlib -nostartfiles + +# The stub dynamic-notes.os should not have weak/undefined symbol magic in it. +# It's not really part of the internals, rather it is a vector for linker magic +# which we need when the linker isn't new enough: +%/dynamic-notes.os: CPPFLAGS += -UMODULE_NAME + +ifeq ($(ld_zunique),yes) +LDFLAGS-c.so += -Wl,-z,unique +endif + # But we still want to link libc.so against $(libc.so-gnulib). LDLIBS-c.so += $(libc.so-gnulib) # Give libc.so an entry point and make it directly runnable itself. @@ -706,6 +717,11 @@ $(common-objpfx)linkobj/libc.so: $(common-objpfx)linkobj/libc_pic.a \ $(build-shlib) $(call after-link,$@) +ifneq ($(ld_zunique),yes) +$(common-objpfx)libc.so: $(common-objpfx)elf/dynamic-notes.os +$(common-objpfx)linkobj/libc.so: $(common-objpfx)elf/dynamic-notes.os +endif + ifeq ($(build-shared),yes) $(common-objpfx)libc.so: $(common-objpfx)libc.map endif diff --git a/configure b/configure index 39d75eb4ed..e191b840dc 100755 --- a/configure +++ b/configure @@ -625,6 +625,7 @@ libc_cv_cc_nofma libc_cv_mtls_dialect_gnu2 fno_unit_at_a_time libc_cv_has_glob_dat +libc_cv_ld_zunique libc_cv_hashstyle libc_cv_fpie libc_cv_z_execstack @@ -6181,9 +6182,46 @@ fi $as_echo "$libc_cv_hashstyle" >&6; } +old_LDFLAGS="$LDFLAGS" +LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared" +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker DT_GNU_FLAGS_1/ DF_GNU_1_UNIQUE support" >&5 +$as_echo_n "checking for linker DT_GNU_FLAGS_1/ DF_GNU_1_UNIQUE support... " >&6; } +if { as_var=cat confdefs.h - <<_ACEOF >conftest.$ac_ext +/* end confdefs.h. */ +void x (void) { } +_ACEOF +if ac_fn_c_try_link "$LINENO"; then : + libc_cv_ld_zunique=yes +else + libc_cv_ld_zunique=no +fi +rm -f core conftest.err conftest.$ac_objext \ + conftest$ac_exeext conftest.$ac_ext; eval \${$as_var+:} false; }; then : + $as_echo_n "(cached) " >&6 +fi +eval ac_res=\$cat confdefs.h - <<_ACEOF >conftest.$ac_ext +/* end confdefs.h. */ +void x (void) { } +_ACEOF +if ac_fn_c_try_link "$LINENO"; then : + libc_cv_ld_zunique=yes +else + libc_cv_ld_zunique=no +fi +rm -f core conftest.err conftest.$ac_objext \ + conftest$ac_exeext conftest.$ac_ext + { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5 +$as_echo "$ac_res" >&6; } +LDFLAGS="$old_LDFLAGS" + +config_vars="$config_vars +ld_zunique = $libc_cv_ld_zunique" + # The linker's default -shared behavior is good enough if it # does these things that our custom linker scripts ensure that -# all allocated NOTE sections come first. +# all allocated NOTE sections come first AND it understands +# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE +# sections in its output. if test "$use_default_link" = default; then { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sufficient default -shared layout" >&5 $as_echo_n "checking for sufficient default -shared layout... " >&6; } @@ -6226,10 +6264,16 @@ EOF esac shift 2 done - case "$libc_seen_a$libc_seen_b" in - yesyes) + case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in + yesyesyes) libc_cv_use_default_link=yes ;; + yesyesno) + echo >&5 "\ +shared layout from: +$ac_try +is OK but -Wl,-z,unique is unsupported so linker scripts are required" + ;; *) echo >&5 "\ $libc_seen_a$libc_seen_b from: diff --git a/configure.ac b/configure.ac index 00f49f09f7..928989fac5 100644 --- a/configure.ac +++ b/configure.ac @@ -1389,9 +1389,21 @@ fi rm -f conftest*]) AC_SUBST(libc_cv_hashstyle) +old_LDFLAGS="$LDFLAGS" +LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared" +AC_CACHE_CHECK([for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support], + AC_LINK_IFELSE([AC_LANG_SOURCE([void foo (void) { }])], + libc_cv_ld_zunique=yes, + libc_cv_ld_zunique=no)) +LDFLAGS="$old_LDFLAGS" +AC_SUBST(libc_cv_ld_zunique) +LIBC_CONFIG_VAR([ld_zunique], [$libc_cv_ld_zunique]) + # The linker's default -shared behavior is good enough if it # does these things that our custom linker scripts ensure that -# all allocated NOTE sections come first. +# all allocated NOTE sections come first AND it understands +# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE +# sections in its output. if test "$use_default_link" = default; then AC_CACHE_CHECK([for sufficient default -shared layout], libc_cv_use_default_link, [dnl @@ -1427,10 +1439,16 @@ EOF esac shift 2 done - case "$libc_seen_a$libc_seen_b" in - yesyes) + case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in + yesyesyes) libc_cv_use_default_link=yes ;; + yesyesno) + echo >&AS_MESSAGE_LOG_FD "\ +shared layout from: +$ac_try +is OK but -Wl,-z,unique is unsupported so linker scripts are required" + ;; *) echo >&AS_MESSAGE_LOG_FD "\ $libc_seen_a$libc_seen_b from: diff --git a/dlfcn/Makefile b/dlfcn/Makefile index 6bbfbb8344..13a2684b30 100644 --- a/dlfcn/Makefile +++ b/dlfcn/Makefile @@ -35,6 +35,7 @@ routines = \ libc_dlerror_result \ extra-libs-others := libdl +not-df-gnu-unique := libdl libdl-shared-only-routines += libdl-compat diff --git a/elf/Makefile b/elf/Makefile index 26986c0692..5157469473 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -104,6 +104,9 @@ endif ifeq (yes,$(build-shared)) extra-objs = $(all-rtld-routines:%=%.os) sofini.os interp.os +ifneq (yes,$(ld_zunique)) +extra-objs += dynamic-notes.os +endif generated += librtld.os dl-allobjs.os ld.so ldd install-others = $(inst_rtlddir)/$(rtld-installed-name) install-bin-script = ldd diff --git a/elf/dynamic-notes.c b/elf/dynamic-notes.c new file mode 100644 index 0000000000..d0b487e970 --- /dev/null +++ b/elf/dynamic-notes.c @@ -0,0 +1,4 @@ +#include + +const ElfW(Dyn) __dynamic_note __attribute__ ((section (".dynamic"))) = + { .d_tag = DT_GNU_FLAGS_1, .d_un.d_val = DF_GNU_1_UNIQUE }; diff --git a/extra-lib.mk b/extra-lib.mk index 72f8d2e1df..e0165c785d 100644 --- a/extra-lib.mk +++ b/extra-lib.mk @@ -101,8 +101,39 @@ $(objpfx)$(lib).so: $(firstword $($(lib)-map) \ $(addprefix $(common-objpfx), \ $(filter $(lib).map, \ $(version-maps)))) + +############################################################################ +# the following have had all functional contents merged back into libc and +# are no longer considered part of the implicitly DF_GNU_1_UNIQUE cluster: +# nptl/libpthread dlfcn/libdl login/libutil resolv/libanl* +# NOTE: htl/libpthread has NOT been merged +# resolv/libanl depends on .../libpthread but it _should_ still be OK +# for resolv/libanl not to be tagged in this case + +# NOTE: the mechanisms are reversed depending on linker support: +# If linker support is present, libraries get the unique flag by default and we +# _suppress_ this with the -z nounique parameter. +# If linker support is absent then the flag is _added_ via a hacked up extra +# object from the elf/ subdir to those DSOs that need it. + +# The not-df-gnu-unique variable should contain a space separated list of +# stub library names (eg pthread for libpthread.so) of extra-libs which should +# NOT have the uniqueness flag. +# It should be set in the Makefile of the relevant subdir: +ifneq ($(ld_zunique),yes) +ifeq (,$(strip $(filter $(not-df-gnu-unique),$(lib)))) +$(objpfx)$(lib).so: $(common-objpfx)/elf/dynamic-notes.os +else endif +else +ifneq (,$(strip $(filter $(not-df-gnu-unique),$(lib)))) +LDFLAGS-$(patsubst lib%,%,$(lib)).so += -Wl,-z,nounique +else +endif +endif +############################################################################ +endif endif # This will define `libof-ROUTINE := LIB' for each of the routines. diff --git a/htl/Makefile b/htl/Makefile index cf9d12fc12..1a807db6ba 100644 --- a/htl/Makefile +++ b/htl/Makefile @@ -169,6 +169,7 @@ shared-only-routines = forward extra-libs := libpthread extra-libs-others := $(extra-libs) +not-df-gnu-unique := install-lib := libpthread.so install-lib-ldscripts := libpthread_syms.a @@ -202,6 +203,7 @@ $(inst_libdir)/libpthread_syms.a: $(srcdir)/libpthread_syms.a $(+force) libc-link.so = $(common-objpfx)libc.so extra-B-pthread.so = -B$(common-objpfx)htl/ +# Turn off DF_GNU_1_UNIQUE for libpthread now that it's a stub. LDFLAGS-pthread.so = -Wl,--enable-new-dtags,-z,nodelete,-z,initfirst include ../Rules diff --git a/iconvdata/Makefile b/iconvdata/Makefile index c216f959df..1209239bc1 100644 --- a/iconvdata/Makefile +++ b/iconvdata/Makefile @@ -67,6 +67,9 @@ modules := ISO8859-1 ISO8859-2 ISO8859-3 ISO8859-4 ISO8859-5 \ ifeq ($(bind-now),yes) LDFLAGS.so += -Wl,-z,now endif +ifeq ($(ld_zunique),yes) +LDFLAGS.so += -Wl,-z,unique +endif modules.so := $(addsuffix .so, $(modules)) diff --git a/iconvdata/extra-module.mk b/iconvdata/extra-module.mk index ecaf507624..5bdceddd80 100644 --- a/iconvdata/extra-module.mk +++ b/iconvdata/extra-module.mk @@ -7,6 +7,10 @@ $(objpfx)$(mod).so: $(addprefix $(objpfx),$(addsuffix .os,$($(mod)-routines)))\ $(shlib-lds) $(link-libc-deps) $(build-module-asneeded) +ifneq ($(ld_zunique),yes) +$(objpfx)$(mod).so: $(common-objpfx)/elf/dynamic-notes.os +endif + ifneq (,$(extra-modules-left)) include extra-module.mk endif diff --git a/login/Makefile b/login/Makefile index 4e6b97734d..703b3f3bd0 100644 --- a/login/Makefile +++ b/login/Makefile @@ -50,6 +50,7 @@ ifeq ($(have-GLIBC_2.33),yes) # Empty compatibility library for old binaries. extra-libs := libutil extra-libs-others := $(extra-libs) +not-df-gnu-unique := libutil libutil-routines := libutil-compat libutil-shared-only-routines := libutil-compat diff --git a/nptl/Makefile b/nptl/Makefile index ff4d590f11..015cbd0b96 100644 --- a/nptl/Makefile +++ b/nptl/Makefile @@ -27,6 +27,7 @@ headers := pthread.h semaphore.h bits/semaphore.h \ extra-libs := libpthread extra-libs-others := $(extra-libs) +not-df-gnu-unique := libpthread routines = \ alloca_cutoff \ @@ -375,7 +376,9 @@ CPPFLAGS-tst-pthread-gdb-attach-static.c := \ # were launched with an explicit ld.so invocation. tst-pthread-gdb-attach-no-pie = yes -tests += tst-cancelx7 tst-cancelx17 +LDFLAGS-pthread.so = -Wl,--enable-new-dtags,-z,nodelete,-z,initfirst + +tests += tst-cancelx7 tst-cancelx17 tst-cleanupx4 ifeq ($(build-shared),yes) tests += tst-compat-forwarder tst-audit-threads diff --git a/resolv/Makefile b/resolv/Makefile index 59e599535c..56afc5c279 100644 --- a/resolv/Makefile +++ b/resolv/Makefile @@ -77,8 +77,10 @@ tests-internal += tst-inet_aton_exact generate := mtrace-tst-leaks.out tst-leaks.mtrace tst-leaks2.mtrace extra-libs := libresolv libnss_dns +not-df-gnu-unique := ifeq ($(have-thread-library),yes) extra-libs += libanl +not-df-gnu-unique += libanl routines += gai_sigqueue tests += \