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Message-ID: <1ee762f8-94e2-baae-0466-deeab0f884f9@redhat.com> Date: Fri, 16 Apr 2021 15:29:53 +0200 From: Harald Hoyer <harald@...hat.com> To: Andy Caldwell <andy.caldwell@...rosoft.com>, musl@...ts.openwall.com Subject: Re: [PATCH] Add static-pie support to musl-gcc Yeah, I have been suggesting this, too <https://www.openwall.com/lists/musl/2020/04/07/2>. Final suggestion was: tools/musl-gcc.specs.sh | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) mode change 100644 => 100755 tools/musl-gcc.specs.sh diff --git a/tools/musl-gcc.specs.sh b/tools/musl-gcc.specs.sh old mode 100644 new mode 100755 index 30492574..ed584ed3 --- a/tools/musl-gcc.specs.sh +++ b/tools/musl-gcc.specs.sh @@ -17,13 +17,13 @@ cat <<EOF libgcc.a%s %:if-exists(libgcc_eh.a%s) *startfile: -%{!shared: $libdir/Scrt1.o} $libdir/crti.o crtbeginS.o%s +%{shared:;static-pie:$libdir/rcrt1.o; :$libdir/Scrt1.o} $libdir/crti.o crtbeginS.o%s *endfile: crtendS.o%s $libdir/crtn.o *link: --dynamic-linker $ldso -nostdlib %{shared:-shared} %{static:-static} %{rdynamic:-export-dynamic} +-dynamic-linker $ldso -nostdlib %{shared:-shared} %{static:-static} %{static-pie:-static -pie --no-dynamic-linker} %{rdynamic:-export-dynamic} *esp_link: Am 15.04.21 um 22:14 schrieb Andy Caldwell: > Hello all, > > I've been using musl as the libc backend for rustc for various and I also wanted > to build some C executables against musl (using the `musl-gcc` wrapper since I'm > compiling on Ubuntu/Centos). For various (security and other) reasons we want > to build `-static-pie` executables but the existing `musl-gcc.specs` file doesn't > handle that flag. I found https://www.openwall.com/lists/musl/2019/05/28/1 > which seemed like a good start, but also seems to have stalled. > > Starting from that patch, I've applied the various suggestions in the following > emails in the thread (adding `-z text` and handling `-eh-frame-hdr`). I've also > make a few other changes: > > * Pass `-pie` to the linker when `-static-pie` is requested (this might be > passed automatically if gcc was built `-default-pie` but it doesn't hurt to > pass it in and it's certainly needed in some cases) > * Don't pass `-dynamic-linker ...` when `-static` is requested (which mirror's > gcc's standard behaviour) > > Using this specfile, I was able to build and run the OpenSSL command line tools > (which seem to be a decent stress-test of a compiler/linker) both as `-static` and > as `-static-pie`, as well as building the compiling the following example > executable to check that PIE is being applied appropriately (compare the > outputs with `-static` vs. `-static-pie` across multiple runs). > > ``` > #include <stdio.h> > > static int static_int = 42; > static int *static_ptr = &static_int; > > int main(int argc, char** argv) { > printf("main: %p, stack: %p, statics: %p\n", main, &argc, static_ptr); > return 0; > } > ``` > > Thanks, > > Andy Caldwell > > --- PATCH BELOW --- > > From 2953e1dc837cd81cac059ea0fa7b4f7bb11c568a Mon Sep 17 00:00:00 2001 > From: Andy Caldwell <andy.caldwell@...rosoft.com> > Date: Thu, 15 Apr 2021 21:05:38 +0100 > Subject: [PATCH] Add static-pie support to musl-gcc > > --- > tools/musl-gcc.specs.sh | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/musl-gcc.specs.sh b/tools/musl-gcc.specs.sh > index 30492574..0e5a9035 100644 > --- a/tools/musl-gcc.specs.sh > +++ b/tools/musl-gcc.specs.sh > @@ -17,13 +17,13 @@ cat <<EOF > libgcc.a%s %:if-exists(libgcc_eh.a%s) > > *startfile: > -%{!shared: $libdir/Scrt1.o} $libdir/crti.o crtbeginS.o%s > +%{static-pie: $libdir/rcrt1.o; !shared: $libdir/Scrt1.o} $libdir/crti.o crtbeginS.o%s > > *endfile: > crtendS.o%s $libdir/crtn.o > > *link: > --dynamic-linker $ldso -nostdlib %{shared:-shared} %{static:-static} %{rdynamic:-export-dynamic} > +%{static-pie: -no-dynamic-linker -pie; !static: -dynamic-linker $ldso} -nostdlib -z text %{shared} %{static-pie|static:-static} %{rdynamic:-export-dynamic} %{!static: -eh-frame-hdr} > > *esp_link: > >
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