[v10,6/7] Add --disable-default-dt-relr
Commit Message
Enable DT_RELR in glibc shared libraries and position independent
executables (PIE) automatically if linker supports -z pack-relative-relocs.
Also add a new configuration option, --disable-default-dt-relr, to
avoid DT_RELR usage in glibc shared libraries and PIEs.
---
INSTALL | 6 ++++++
Makeconfig | 19 +++++++++++++++++++
Makerules | 2 ++
configure | 18 ++++++++++++++++++
configure.ac | 13 +++++++++++++
elf/Makefile | 4 +++-
manual/install.texi | 5 +++++
7 files changed, 66 insertions(+), 1 deletion(-)
Comments
On 14/04/2022 20:21, H.J. Lu wrote:
> Enable DT_RELR in glibc shared libraries and position independent
> executables (PIE) automatically if linker supports -z pack-relative-relocs.
>
> Also add a new configuration option, --disable-default-dt-relr, to
> avoid DT_RELR usage in glibc shared libraries and PIEs.
Patch looks ok but I am trying to see which would be a usercase for the
--disable-default-dt-relr since loader and libc are tied together and
we don't really support mixing up build with different configure
options (although in practice I think most combination would work).
I take that DT_RELR is always an improvement for shared libraries and
PIE, specially the ones with a lot o irelative relocations.
> ---
> INSTALL | 6 ++++++
> Makeconfig | 19 +++++++++++++++++++
> Makerules | 2 ++
> configure | 18 ++++++++++++++++++
> configure.ac | 13 +++++++++++++
> elf/Makefile | 4 +++-
> manual/install.texi | 5 +++++
> 7 files changed, 66 insertions(+), 1 deletion(-)
>
> diff --git a/INSTALL b/INSTALL
> index 63c022d6b9..4a6506f11f 100644
> --- a/INSTALL
> +++ b/INSTALL
> @@ -133,6 +133,12 @@ if 'CFLAGS' is specified it must enable optimization. For example:
> used with the GCC option, -static-pie, which is available with GCC
> 8 or above, to create static PIE.
>
> +'--disable-default-dt-relr'
> + Don't enable DT_RELR in glibc shared libraries and position
> + independent executables (PIE). By default, DT_RELR is enabled in
Two space after period.
> + glibc shared libraries and position independent executables on
> + targets that support it.
> +
> '--enable-cet'
> '--enable-cet=permissive'
> Enable Intel Control-flow Enforcement Technology (CET) support.
> diff --git a/Makeconfig b/Makeconfig
> index 0aa5fb0099..b75f28f837 100644
> --- a/Makeconfig
> +++ b/Makeconfig
> @@ -358,6 +358,23 @@ else
> real-static-start-installed-name = $(static-start-installed-name)
> endif
>
> +# Linker option to enable and disable DT-RELR.
> +ifeq ($(have-dt-relr),yes)
> +dt-relr-ldflag = -Wl,-z,pack-relative-relocs
> +no-dt-relr-ldflag = -Wl,-z,nopack-relative-relocs
> +else
> +dt-relr-ldflag =
> +no-dt-relr-ldflag =
> +endif
> +
> +# Default linker option for DT-RELR.
> +ifeq (yes,$(build-dt-relr-default))
> +default-rt-relr-ldflag = $(dt-relr-ldflag)
> +else
> +default-rt-relr-ldflag = $(no-dt-relr-ldflag)
> +endif
> +LDFLAGS-rtld += $(default-rt-relr-ldflag)
> +
> relro-LDFLAGS = -Wl,-z,relro
> LDFLAGS.so += $(relro-LDFLAGS)
> LDFLAGS-rtld += $(relro-LDFLAGS)
> @@ -413,6 +430,7 @@ link-extra-libs-tests = $(libsupport)
> # Command for linking PIE programs with the C library.
> ifndef +link-pie
> +link-pie-before-inputs = $(if $($(@F)-no-pie),$(no-pie-ldflag),-pie) \
> + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
> -Wl,-O1 -nostdlib -nostartfiles \
> $(sysdep-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F)) \
> $(relro-LDFLAGS) $(hashstyle-LDFLAGS) \
> @@ -445,6 +463,7 @@ endif
> ifndef +link-static
> +link-static-before-inputs = -nostdlib -nostartfiles -static \
> $(if $($(@F)-no-pie),$(no-pie-ldflag),$(static-pie-ldflag)) \
> + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
> $(sysdep-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F)) \
> $(firstword $(CRT-$(@F)) $(csu-objpfx)$(real-static-start-installed-name)) \
> $(+preinit) $(+prectorT)
> diff --git a/Makerules b/Makerules
> index 428464f092..7c1da551bf 100644
> --- a/Makerules
> +++ b/Makerules
> @@ -536,6 +536,7 @@ lib%.so: lib%_pic.a $(+preinit) $(+postinit) $(link-libc-deps)
> define build-shlib-helper
> $(LINK.o) -shared -static-libgcc -Wl,-O1 $(sysdep-LDFLAGS) \
> $(if $($(@F)-no-z-defs)$(no-z-defs),,-Wl,-z,defs) $(rtld-LDFLAGS) \
> + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
> $(extra-B-$(@F:lib%.so=%).so) -B$(csu-objpfx) \
> $(extra-B-$(@F:lib%.so=%).so) $(load-map-file) \
> -Wl,-soname=lib$(libprefix)$(@F:lib%.so=%).so$($(@F)-version) \
> @@ -595,6 +596,7 @@ endef
> define build-module-helper
> $(LINK.o) -shared -static-libgcc $(sysdep-LDFLAGS) $(rtld-LDFLAGS) \
> $(if $($(@F)-no-z-defs)$(no-z-defs),,-Wl,-z,defs) \
> + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
> -B$(csu-objpfx) $(load-map-file) \
> $(LDFLAGS.so) $(LDFLAGS-$(@F:%.so=%).so) \
> $(link-test-modules-rpath-link) \
> diff --git a/configure b/configure
> index c0c2246597..d230c2c673 100755
> --- a/configure
> +++ b/configure
> @@ -767,6 +767,7 @@ enable_sanity_checks
> enable_shared
> enable_profile
> enable_default_pie
> +enable_default_dt_relr
> enable_timezone_tools
> enable_hardcoded_path_in_tests
> enable_hidden_plt
> @@ -1424,6 +1425,7 @@ Optional Features:
> --enable-profile build profiled library [default=no]
> --disable-default-pie Do not build glibc programs and the testsuite as PIE
> [default=no]
> + --disable-dt-relr Do not enable DT_RELR in glibc[default=no]
> --disable-timezone-tools
> do not install timezone tools [default=install]
> --enable-hardcoded-path-in-tests
> @@ -3440,6 +3442,13 @@ else
> default_pie=yes
> fi
>
> +# Check whether --enable-default-dt-relr was given.
> +if test "${enable_default_dt_relr+set}" = set; then :
> + enableval=$enable_default_dt_relr; default_dt_relr=$enableval
> +else
> + default_dt_relr=yes
> +fi
> +
> # Check whether --enable-timezone-tools was given.
> if test "${enable_timezone_tools+set}" = set; then :
> enableval=$enable_timezone_tools; enable_timezone_tools=$enableval
> @@ -7092,6 +7101,15 @@ fi
> config_vars="$config_vars
> enable-static-pie = $libc_cv_static_pie"
>
> +# Disable build-dt-relr-default if linker does not support it or if glibc
> +# is configured with --disable-default-dt-relr.
> +build_dt_relr_default=$default_dt_relr
> +if test "x$build_dt_relr_default" != xno; then
> + build_dt_relr_default=$libc_cv_dt_relr
> +fi
> +config_vars="$config_vars
> +build-dt-relr-default = $build_dt_relr_default"
> +
> # Set the `multidir' variable by grabbing the variable from the compiler.
> # We do it once and save the result in a generated makefile.
> libc_cv_multidir=`${CC-cc} $CFLAGS $CPPFLAGS -print-multi-directory`
> diff --git a/configure.ac b/configure.ac
> index 66cad71431..1aa152b901 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -197,6 +197,11 @@ AC_ARG_ENABLE([default-pie],
> [Do not build glibc programs and the testsuite as PIE @<:@default=no@:>@]),
> [default_pie=$enableval],
> [default_pie=yes])
> +AC_ARG_ENABLE([default-dt-relr],
> + AS_HELP_STRING([--disable-dt-relr],
> + [Do not enable DT_RELR in glibc@<:@default=no@:>@]),
Missing space after 'glibc'.
> + [default_dt_relr=$enableval],
> + [default_dt_relr=yes])
> AC_ARG_ENABLE([timezone-tools],
> AS_HELP_STRING([--disable-timezone-tools],
> [do not install timezone tools @<:@default=install@:>@]),
> @@ -1878,6 +1883,14 @@ if test "$libc_cv_static_pie" = "yes"; then
> fi
> LIBC_CONFIG_VAR([enable-static-pie], [$libc_cv_static_pie])
>
> +# Disable build-dt-relr-default if linker does not support it or if glibc
> +# is configured with --disable-default-dt-relr.
> +build_dt_relr_default=$default_dt_relr
> +if test "x$build_dt_relr_default" != xno; then
> + build_dt_relr_default=$libc_cv_dt_relr
> +fi
> +LIBC_CONFIG_VAR([build-dt-relr-default], [$build_dt_relr_default])
> +
> # Set the `multidir' variable by grabbing the variable from the compiler.
> # We do it once and save the result in a generated makefile.
> libc_cv_multidir=`${CC-cc} $CFLAGS $CPPFLAGS -print-multi-directory`
> diff --git a/elf/Makefile b/elf/Makefile
> index 07ac9ec3ef..bf8a61dc30 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -1603,6 +1603,7 @@ $(objpfx)nodlopen2.out: $(objpfx)nodlopenmod2.so
>
> $(objpfx)filtmod1.so: $(objpfx)filtmod1.os $(objpfx)filtmod2.so
> $(LINK.o) -shared -o $@ -B$(csu-objpfx) $(LDFLAGS.so) \
> + $(default-rt-relr-ldflag) \
> -L$(subst :, -L,$(rpath-link)) \
> -Wl,-rpath-link=$(rpath-link) \
> $< -Wl,-F,$(objpfx)filtmod2.so
> @@ -2402,7 +2403,7 @@ $(objpfx)tst-big-note: $(objpfx)tst-big-note-lib.so
> # artificial, large note in tst-big-note-lib.o and invalidate the
> # test.
> $(objpfx)tst-big-note-lib.so: $(objpfx)tst-big-note-lib.o
> - $(LINK.o) -shared -o $@ $(LDFLAGS.so) $<
> + $(LINK.o) -shared -o $@ $(LDFLAGS.so) $(default-rt-relr-ldflag) $<
>
> $(objpfx)tst-unwind-ctor: $(objpfx)tst-unwind-ctor-lib.so
>
> @@ -2711,6 +2712,7 @@ $(objpfx)tst-ro-dynamic: $(objpfx)tst-ro-dynamic-mod.so
> $(objpfx)tst-ro-dynamic-mod.so: $(objpfx)tst-ro-dynamic-mod.os \
> tst-ro-dynamic-mod.map
> $(LINK.o) -nostdlib -nostartfiles -shared -o $@ \
> + $(default-rt-relr-ldflag) \
> -Wl,--script=tst-ro-dynamic-mod.map \
> $(objpfx)tst-ro-dynamic-mod.os
>
> diff --git a/manual/install.texi b/manual/install.texi
> index 29c52f2927..04ea996561 100644
> --- a/manual/install.texi
> +++ b/manual/install.texi
> @@ -161,6 +161,11 @@ and architecture support it, static executables are built as static PIE and the
> resulting glibc can be used with the GCC option, -static-pie, which is
> available with GCC 8 or above, to create static PIE.
>
> +@item --disable-default-dt-relr
> +Don't enable DT_RELR in glibc shared libraries and position independent
> +executables (PIE). By default, DT_RELR is enabled in glibc shared
> +libraries and position independent executables on targets that support it.
> +
> @item --enable-cet
> @itemx --enable-cet=permissive
> Enable Intel Control-flow Enforcement Technology (CET) support. When
On Wed, Apr 20, 2022 at 10:49 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 14/04/2022 20:21, H.J. Lu wrote:
> > Enable DT_RELR in glibc shared libraries and position independent
> > executables (PIE) automatically if linker supports -z pack-relative-relocs.
> >
> > Also add a new configuration option, --disable-default-dt-relr, to
> > avoid DT_RELR usage in glibc shared libraries and PIEs.
>
> Patch looks ok but I am trying to see which would be a usercase for the
> --disable-default-dt-relr since loader and libc are tied together and
> we don't really support mixing up build with different configure
> options (although in practice I think most combination would work).
>
> I take that DT_RELR is always an improvement for shared libraries and
> PIE, specially the ones with a lot o irelative relocations.
This is an option. I don't mind dropping it.
> > ---
> > INSTALL | 6 ++++++
> > Makeconfig | 19 +++++++++++++++++++
> > Makerules | 2 ++
> > configure | 18 ++++++++++++++++++
> > configure.ac | 13 +++++++++++++
> > elf/Makefile | 4 +++-
> > manual/install.texi | 5 +++++
> > 7 files changed, 66 insertions(+), 1 deletion(-)
> >
> > diff --git a/INSTALL b/INSTALL
> > index 63c022d6b9..4a6506f11f 100644
> > --- a/INSTALL
> > +++ b/INSTALL
> > @@ -133,6 +133,12 @@ if 'CFLAGS' is specified it must enable optimization. For example:
> > used with the GCC option, -static-pie, which is available with GCC
> > 8 or above, to create static PIE.
> >
> > +'--disable-default-dt-relr'
> > + Don't enable DT_RELR in glibc shared libraries and position
> > + independent executables (PIE). By default, DT_RELR is enabled in
>
> Two space after period.
This is a generated file. The original change in manual/install.texi
has 2 spaces.
> > + glibc shared libraries and position independent executables on
> > + targets that support it.
> > +
> > '--enable-cet'
> > '--enable-cet=permissive'
> > Enable Intel Control-flow Enforcement Technology (CET) support.
> > diff --git a/Makeconfig b/Makeconfig
> > index 0aa5fb0099..b75f28f837 100644
> > --- a/Makeconfig
> > +++ b/Makeconfig
> > @@ -358,6 +358,23 @@ else
> > real-static-start-installed-name = $(static-start-installed-name)
> > endif
> >
> > +# Linker option to enable and disable DT-RELR.
> > +ifeq ($(have-dt-relr),yes)
> > +dt-relr-ldflag = -Wl,-z,pack-relative-relocs
> > +no-dt-relr-ldflag = -Wl,-z,nopack-relative-relocs
> > +else
> > +dt-relr-ldflag =
> > +no-dt-relr-ldflag =
> > +endif
> > +
> > +# Default linker option for DT-RELR.
> > +ifeq (yes,$(build-dt-relr-default))
> > +default-rt-relr-ldflag = $(dt-relr-ldflag)
> > +else
> > +default-rt-relr-ldflag = $(no-dt-relr-ldflag)
> > +endif
> > +LDFLAGS-rtld += $(default-rt-relr-ldflag)
> > +
> > relro-LDFLAGS = -Wl,-z,relro
> > LDFLAGS.so += $(relro-LDFLAGS)
> > LDFLAGS-rtld += $(relro-LDFLAGS)
> > @@ -413,6 +430,7 @@ link-extra-libs-tests = $(libsupport)
> > # Command for linking PIE programs with the C library.
> > ifndef +link-pie
> > +link-pie-before-inputs = $(if $($(@F)-no-pie),$(no-pie-ldflag),-pie) \
> > + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
> > -Wl,-O1 -nostdlib -nostartfiles \
> > $(sysdep-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F)) \
> > $(relro-LDFLAGS) $(hashstyle-LDFLAGS) \
> > @@ -445,6 +463,7 @@ endif
> > ifndef +link-static
> > +link-static-before-inputs = -nostdlib -nostartfiles -static \
> > $(if $($(@F)-no-pie),$(no-pie-ldflag),$(static-pie-ldflag)) \
> > + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
> > $(sysdep-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F)) \
> > $(firstword $(CRT-$(@F)) $(csu-objpfx)$(real-static-start-installed-name)) \
> > $(+preinit) $(+prectorT)
> > diff --git a/Makerules b/Makerules
> > index 428464f092..7c1da551bf 100644
> > --- a/Makerules
> > +++ b/Makerules
> > @@ -536,6 +536,7 @@ lib%.so: lib%_pic.a $(+preinit) $(+postinit) $(link-libc-deps)
> > define build-shlib-helper
> > $(LINK.o) -shared -static-libgcc -Wl,-O1 $(sysdep-LDFLAGS) \
> > $(if $($(@F)-no-z-defs)$(no-z-defs),,-Wl,-z,defs) $(rtld-LDFLAGS) \
> > + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
> > $(extra-B-$(@F:lib%.so=%).so) -B$(csu-objpfx) \
> > $(extra-B-$(@F:lib%.so=%).so) $(load-map-file) \
> > -Wl,-soname=lib$(libprefix)$(@F:lib%.so=%).so$($(@F)-version) \
> > @@ -595,6 +596,7 @@ endef
> > define build-module-helper
> > $(LINK.o) -shared -static-libgcc $(sysdep-LDFLAGS) $(rtld-LDFLAGS) \
> > $(if $($(@F)-no-z-defs)$(no-z-defs),,-Wl,-z,defs) \
> > + $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
> > -B$(csu-objpfx) $(load-map-file) \
> > $(LDFLAGS.so) $(LDFLAGS-$(@F:%.so=%).so) \
> > $(link-test-modules-rpath-link) \
> > diff --git a/configure b/configure
> > index c0c2246597..d230c2c673 100755
> > --- a/configure
> > +++ b/configure
> > @@ -767,6 +767,7 @@ enable_sanity_checks
> > enable_shared
> > enable_profile
> > enable_default_pie
> > +enable_default_dt_relr
> > enable_timezone_tools
> > enable_hardcoded_path_in_tests
> > enable_hidden_plt
> > @@ -1424,6 +1425,7 @@ Optional Features:
> > --enable-profile build profiled library [default=no]
> > --disable-default-pie Do not build glibc programs and the testsuite as PIE
> > [default=no]
> > + --disable-dt-relr Do not enable DT_RELR in glibc[default=no]
> > --disable-timezone-tools
> > do not install timezone tools [default=install]
> > --enable-hardcoded-path-in-tests
> > @@ -3440,6 +3442,13 @@ else
> > default_pie=yes
> > fi
> >
> > +# Check whether --enable-default-dt-relr was given.
> > +if test "${enable_default_dt_relr+set}" = set; then :
> > + enableval=$enable_default_dt_relr; default_dt_relr=$enableval
> > +else
> > + default_dt_relr=yes
> > +fi
> > +
> > # Check whether --enable-timezone-tools was given.
> > if test "${enable_timezone_tools+set}" = set; then :
> > enableval=$enable_timezone_tools; enable_timezone_tools=$enableval
> > @@ -7092,6 +7101,15 @@ fi
> > config_vars="$config_vars
> > enable-static-pie = $libc_cv_static_pie"
> >
> > +# Disable build-dt-relr-default if linker does not support it or if glibc
> > +# is configured with --disable-default-dt-relr.
> > +build_dt_relr_default=$default_dt_relr
> > +if test "x$build_dt_relr_default" != xno; then
> > + build_dt_relr_default=$libc_cv_dt_relr
> > +fi
> > +config_vars="$config_vars
> > +build-dt-relr-default = $build_dt_relr_default"
> > +
> > # Set the `multidir' variable by grabbing the variable from the compiler.
> > # We do it once and save the result in a generated makefile.
> > libc_cv_multidir=`${CC-cc} $CFLAGS $CPPFLAGS -print-multi-directory`
> > diff --git a/configure.ac b/configure.ac
> > index 66cad71431..1aa152b901 100644
> > --- a/configure.ac
> > +++ b/configure.ac
> > @@ -197,6 +197,11 @@ AC_ARG_ENABLE([default-pie],
> > [Do not build glibc programs and the testsuite as PIE @<:@default=no@:>@]),
> > [default_pie=$enableval],
> > [default_pie=yes])
> > +AC_ARG_ENABLE([default-dt-relr],
> > + AS_HELP_STRING([--disable-dt-relr],
> > + [Do not enable DT_RELR in glibc@<:@default=no@:>@]),
>
> Missing space after 'glibc'.
Fixed in v11.
>
> > + [default_dt_relr=$enableval],
> > + [default_dt_relr=yes])
> > AC_ARG_ENABLE([timezone-tools],
> > AS_HELP_STRING([--disable-timezone-tools],
> > [do not install timezone tools @<:@default=install@:>@]),
> > @@ -1878,6 +1883,14 @@ if test "$libc_cv_static_pie" = "yes"; then
> > fi
> > LIBC_CONFIG_VAR([enable-static-pie], [$libc_cv_static_pie])
> >
> > +# Disable build-dt-relr-default if linker does not support it or if glibc
> > +# is configured with --disable-default-dt-relr.
> > +build_dt_relr_default=$default_dt_relr
> > +if test "x$build_dt_relr_default" != xno; then
> > + build_dt_relr_default=$libc_cv_dt_relr
> > +fi
> > +LIBC_CONFIG_VAR([build-dt-relr-default], [$build_dt_relr_default])
> > +
> > # Set the `multidir' variable by grabbing the variable from the compiler.
> > # We do it once and save the result in a generated makefile.
> > libc_cv_multidir=`${CC-cc} $CFLAGS $CPPFLAGS -print-multi-directory`
> > diff --git a/elf/Makefile b/elf/Makefile
> > index 07ac9ec3ef..bf8a61dc30 100644
> > --- a/elf/Makefile
> > +++ b/elf/Makefile
> > @@ -1603,6 +1603,7 @@ $(objpfx)nodlopen2.out: $(objpfx)nodlopenmod2.so
> >
> > $(objpfx)filtmod1.so: $(objpfx)filtmod1.os $(objpfx)filtmod2.so
> > $(LINK.o) -shared -o $@ -B$(csu-objpfx) $(LDFLAGS.so) \
> > + $(default-rt-relr-ldflag) \
> > -L$(subst :, -L,$(rpath-link)) \
> > -Wl,-rpath-link=$(rpath-link) \
> > $< -Wl,-F,$(objpfx)filtmod2.so
> > @@ -2402,7 +2403,7 @@ $(objpfx)tst-big-note: $(objpfx)tst-big-note-lib.so
> > # artificial, large note in tst-big-note-lib.o and invalidate the
> > # test.
> > $(objpfx)tst-big-note-lib.so: $(objpfx)tst-big-note-lib.o
> > - $(LINK.o) -shared -o $@ $(LDFLAGS.so) $<
> > + $(LINK.o) -shared -o $@ $(LDFLAGS.so) $(default-rt-relr-ldflag) $<
> >
> > $(objpfx)tst-unwind-ctor: $(objpfx)tst-unwind-ctor-lib.so
> >
> > @@ -2711,6 +2712,7 @@ $(objpfx)tst-ro-dynamic: $(objpfx)tst-ro-dynamic-mod.so
> > $(objpfx)tst-ro-dynamic-mod.so: $(objpfx)tst-ro-dynamic-mod.os \
> > tst-ro-dynamic-mod.map
> > $(LINK.o) -nostdlib -nostartfiles -shared -o $@ \
> > + $(default-rt-relr-ldflag) \
> > -Wl,--script=tst-ro-dynamic-mod.map \
> > $(objpfx)tst-ro-dynamic-mod.os
> >
> > diff --git a/manual/install.texi b/manual/install.texi
> > index 29c52f2927..04ea996561 100644
> > --- a/manual/install.texi
> > +++ b/manual/install.texi
> > @@ -161,6 +161,11 @@ and architecture support it, static executables are built as static PIE and the
> > resulting glibc can be used with the GCC option, -static-pie, which is
> > available with GCC 8 or above, to create static PIE.
> >
> > +@item --disable-default-dt-relr
> > +Don't enable DT_RELR in glibc shared libraries and position independent
> > +executables (PIE). By default, DT_RELR is enabled in glibc shared
There are 2 spaces here.
> > +libraries and position independent executables on targets that support it.
> > +
> > @item --enable-cet
> > @itemx --enable-cet=permissive
> > Enable Intel Control-flow Enforcement Technology (CET) support. When
Thanks.
@@ -133,6 +133,12 @@ if 'CFLAGS' is specified it must enable optimization. For example:
used with the GCC option, -static-pie, which is available with GCC
8 or above, to create static PIE.
+'--disable-default-dt-relr'
+ Don't enable DT_RELR in glibc shared libraries and position
+ independent executables (PIE). By default, DT_RELR is enabled in
+ glibc shared libraries and position independent executables on
+ targets that support it.
+
'--enable-cet'
'--enable-cet=permissive'
Enable Intel Control-flow Enforcement Technology (CET) support.
@@ -358,6 +358,23 @@ else
real-static-start-installed-name = $(static-start-installed-name)
endif
+# Linker option to enable and disable DT-RELR.
+ifeq ($(have-dt-relr),yes)
+dt-relr-ldflag = -Wl,-z,pack-relative-relocs
+no-dt-relr-ldflag = -Wl,-z,nopack-relative-relocs
+else
+dt-relr-ldflag =
+no-dt-relr-ldflag =
+endif
+
+# Default linker option for DT-RELR.
+ifeq (yes,$(build-dt-relr-default))
+default-rt-relr-ldflag = $(dt-relr-ldflag)
+else
+default-rt-relr-ldflag = $(no-dt-relr-ldflag)
+endif
+LDFLAGS-rtld += $(default-rt-relr-ldflag)
+
relro-LDFLAGS = -Wl,-z,relro
LDFLAGS.so += $(relro-LDFLAGS)
LDFLAGS-rtld += $(relro-LDFLAGS)
@@ -413,6 +430,7 @@ link-extra-libs-tests = $(libsupport)
# Command for linking PIE programs with the C library.
ifndef +link-pie
+link-pie-before-inputs = $(if $($(@F)-no-pie),$(no-pie-ldflag),-pie) \
+ $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
-Wl,-O1 -nostdlib -nostartfiles \
$(sysdep-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F)) \
$(relro-LDFLAGS) $(hashstyle-LDFLAGS) \
@@ -445,6 +463,7 @@ endif
ifndef +link-static
+link-static-before-inputs = -nostdlib -nostartfiles -static \
$(if $($(@F)-no-pie),$(no-pie-ldflag),$(static-pie-ldflag)) \
+ $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
$(sysdep-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F)) \
$(firstword $(CRT-$(@F)) $(csu-objpfx)$(real-static-start-installed-name)) \
$(+preinit) $(+prectorT)
@@ -536,6 +536,7 @@ lib%.so: lib%_pic.a $(+preinit) $(+postinit) $(link-libc-deps)
define build-shlib-helper
$(LINK.o) -shared -static-libgcc -Wl,-O1 $(sysdep-LDFLAGS) \
$(if $($(@F)-no-z-defs)$(no-z-defs),,-Wl,-z,defs) $(rtld-LDFLAGS) \
+ $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
$(extra-B-$(@F:lib%.so=%).so) -B$(csu-objpfx) \
$(extra-B-$(@F:lib%.so=%).so) $(load-map-file) \
-Wl,-soname=lib$(libprefix)$(@F:lib%.so=%).so$($(@F)-version) \
@@ -595,6 +596,7 @@ endef
define build-module-helper
$(LINK.o) -shared -static-libgcc $(sysdep-LDFLAGS) $(rtld-LDFLAGS) \
$(if $($(@F)-no-z-defs)$(no-z-defs),,-Wl,-z,defs) \
+ $(if $($(@F)-no-dt-relr),$(no-dt-relr-ldflag),$(default-rt-relr-ldflag)) \
-B$(csu-objpfx) $(load-map-file) \
$(LDFLAGS.so) $(LDFLAGS-$(@F:%.so=%).so) \
$(link-test-modules-rpath-link) \
@@ -767,6 +767,7 @@ enable_sanity_checks
enable_shared
enable_profile
enable_default_pie
+enable_default_dt_relr
enable_timezone_tools
enable_hardcoded_path_in_tests
enable_hidden_plt
@@ -1424,6 +1425,7 @@ Optional Features:
--enable-profile build profiled library [default=no]
--disable-default-pie Do not build glibc programs and the testsuite as PIE
[default=no]
+ --disable-dt-relr Do not enable DT_RELR in glibc[default=no]
--disable-timezone-tools
do not install timezone tools [default=install]
--enable-hardcoded-path-in-tests
@@ -3440,6 +3442,13 @@ else
default_pie=yes
fi
+# Check whether --enable-default-dt-relr was given.
+if test "${enable_default_dt_relr+set}" = set; then :
+ enableval=$enable_default_dt_relr; default_dt_relr=$enableval
+else
+ default_dt_relr=yes
+fi
+
# Check whether --enable-timezone-tools was given.
if test "${enable_timezone_tools+set}" = set; then :
enableval=$enable_timezone_tools; enable_timezone_tools=$enableval
@@ -7092,6 +7101,15 @@ fi
config_vars="$config_vars
enable-static-pie = $libc_cv_static_pie"
+# Disable build-dt-relr-default if linker does not support it or if glibc
+# is configured with --disable-default-dt-relr.
+build_dt_relr_default=$default_dt_relr
+if test "x$build_dt_relr_default" != xno; then
+ build_dt_relr_default=$libc_cv_dt_relr
+fi
+config_vars="$config_vars
+build-dt-relr-default = $build_dt_relr_default"
+
# Set the `multidir' variable by grabbing the variable from the compiler.
# We do it once and save the result in a generated makefile.
libc_cv_multidir=`${CC-cc} $CFLAGS $CPPFLAGS -print-multi-directory`
@@ -197,6 +197,11 @@ AC_ARG_ENABLE([default-pie],
[Do not build glibc programs and the testsuite as PIE @<:@default=no@:>@]),
[default_pie=$enableval],
[default_pie=yes])
+AC_ARG_ENABLE([default-dt-relr],
+ AS_HELP_STRING([--disable-dt-relr],
+ [Do not enable DT_RELR in glibc@<:@default=no@:>@]),
+ [default_dt_relr=$enableval],
+ [default_dt_relr=yes])
AC_ARG_ENABLE([timezone-tools],
AS_HELP_STRING([--disable-timezone-tools],
[do not install timezone tools @<:@default=install@:>@]),
@@ -1878,6 +1883,14 @@ if test "$libc_cv_static_pie" = "yes"; then
fi
LIBC_CONFIG_VAR([enable-static-pie], [$libc_cv_static_pie])
+# Disable build-dt-relr-default if linker does not support it or if glibc
+# is configured with --disable-default-dt-relr.
+build_dt_relr_default=$default_dt_relr
+if test "x$build_dt_relr_default" != xno; then
+ build_dt_relr_default=$libc_cv_dt_relr
+fi
+LIBC_CONFIG_VAR([build-dt-relr-default], [$build_dt_relr_default])
+
# Set the `multidir' variable by grabbing the variable from the compiler.
# We do it once and save the result in a generated makefile.
libc_cv_multidir=`${CC-cc} $CFLAGS $CPPFLAGS -print-multi-directory`
@@ -1603,6 +1603,7 @@ $(objpfx)nodlopen2.out: $(objpfx)nodlopenmod2.so
$(objpfx)filtmod1.so: $(objpfx)filtmod1.os $(objpfx)filtmod2.so
$(LINK.o) -shared -o $@ -B$(csu-objpfx) $(LDFLAGS.so) \
+ $(default-rt-relr-ldflag) \
-L$(subst :, -L,$(rpath-link)) \
-Wl,-rpath-link=$(rpath-link) \
$< -Wl,-F,$(objpfx)filtmod2.so
@@ -2402,7 +2403,7 @@ $(objpfx)tst-big-note: $(objpfx)tst-big-note-lib.so
# artificial, large note in tst-big-note-lib.o and invalidate the
# test.
$(objpfx)tst-big-note-lib.so: $(objpfx)tst-big-note-lib.o
- $(LINK.o) -shared -o $@ $(LDFLAGS.so) $<
+ $(LINK.o) -shared -o $@ $(LDFLAGS.so) $(default-rt-relr-ldflag) $<
$(objpfx)tst-unwind-ctor: $(objpfx)tst-unwind-ctor-lib.so
@@ -2711,6 +2712,7 @@ $(objpfx)tst-ro-dynamic: $(objpfx)tst-ro-dynamic-mod.so
$(objpfx)tst-ro-dynamic-mod.so: $(objpfx)tst-ro-dynamic-mod.os \
tst-ro-dynamic-mod.map
$(LINK.o) -nostdlib -nostartfiles -shared -o $@ \
+ $(default-rt-relr-ldflag) \
-Wl,--script=tst-ro-dynamic-mod.map \
$(objpfx)tst-ro-dynamic-mod.os
@@ -161,6 +161,11 @@ and architecture support it, static executables are built as static PIE and the
resulting glibc can be used with the GCC option, -static-pie, which is
available with GCC 8 or above, to create static PIE.
+@item --disable-default-dt-relr
+Don't enable DT_RELR in glibc shared libraries and position independent
+executables (PIE). By default, DT_RELR is enabled in glibc shared
+libraries and position independent executables on targets that support it.
+
@item --enable-cet
@itemx --enable-cet=permissive
Enable Intel Control-flow Enforcement Technology (CET) support. When