cmd/link: support PIE when using the external linker #6940

gopherbot · 2013-12-12T16:00:23Z

by peter.volkov:

I'm building current tip of go and one test fails:

--- FAIL: TestCgoCrashHandler (1.02 seconds)
    crash_test.go:80: output:
        # command-line-arguments
        /usr/lib/gcc/x86_64-pc-linux-gnu/4.7.3/../../../../x86_64-pc-linux-gnu/bin/ld: /var/tmp/go-link-ynzhxL/go.o: relocation R_X86_64_32 against `main.func·001·f' can not be used when making a shared object; recompile with -fPIC
        /var/tmp/go-link-ynzhxL/go.o: could not read symbols: Bad value
        collect2: error: ld returned 1 exit status
        /home/peter/projects/go/go/pkg/tool/linux_amd64/6l: running gcc failed: unsuccessful exit status 0x100
        
        
        wanted:
        main: recovered done
        new-thread: recovered done
        second-new-thread: recovered done
        main-again: recovered done
--- FAIL: TestCgoSignalDeadlock (0.75 seconds)
    crash_cgo_test.go:25: expected "OK\n", but got "# command-line-arguments\n/usr/lib/gcc/x86_64-pc-linux-gnu/4.7.3/../../../../x86_64-pc-linux-gnu/bin/ld: /var/tmp/go-link-T4Mx9x/go.o: relocation R_X86_64_32 against `type.*' can not be used when making a shared object; recompile with -fPIC\n/var/tmp/go-link-T4Mx9x/go.o: could not read symbols: Bad value\ncollect2: error: ld returned 1 exit status\n/home/peter/projects/go/go/pkg/tool/linux_amd64/6l: running gcc failed: unsuccessful exit status 0x100\n"
--- FAIL: TestCgoTraceback (0.88 seconds)
    crash_cgo_test.go:33: expected "OK\n", but got "# command-line-arguments\n/usr/lib/gcc/x86_64-pc-linux-gnu/4.7.3/../../../../x86_64-pc-linux-gnu/bin/ld: /var/tmp/go-link-WdQPCq/go.o: relocation R_X86_64_32 against `type.*' can not be used when making a shared object; recompile with -fPIC\n/var/tmp/go-link-WdQPCq/go.o: could not read symbols: Bad value\ncollect2: error: ld returned 1 exit status\n/home/peter/projects/go/go/pkg/tool/linux_amd64/6l: running gcc failed: unsuccessful exit status 0x100\n"
FAIL
FAIL    runtime 15.776s


go version devel +1e3f306f9d46 Thu Dec 12 06:40:16 2013 -0800 linux/amd64

minux · 2013-12-13T05:48:52Z

Comment 1:

do you any special setup?
I was puzzled by the fact that those tests used the external linking mode.
you can take a look at the source code embedded in pkg/runtime/crash_cgo_test.go, and
copy them out and "go run" them to see you can reproduce the problem.

Status changed to WaitingForReply.

minux · 2013-12-13T05:52:37Z

Comment 2:

(I can't reproduce this problem even with external linking on linux/amd64)

gopherbot · 2013-12-13T20:19:04Z

Comment 3 by peter.volkov:

Well, can reproduce the problem with that embedded code.
 $ go build 3.go
# command-line-arguments
/usr/lib/gcc/x86_64-pc-linux-gnu/4.7.3/../../../../x86_64-pc-linux-gnu/bin/ld:
/var/tmp/go-link-Nhb93l/go.o: relocation R_X86_64_32 against `type.*' can not be used
when making a shared object; recompile with -fPIC
/var/tmp/go-link-Nhb93l/go.o: could not read symbols: Bad value
collect2: error: ld returned 1 exit status
/home/peter/projects/go/go/pkg/tool/linux_amd64/6l: running gcc failed: unsuccessful
exit status 0x100
About environment: this is hardened gentoo linux.
Portage 2.2.7 (hardened/linux/amd64, gcc-4.7.3, glibc-2.17, 3.11.7-hardened x86_64)
=================================================================
System uname:
Linux-3.11.7-hardened-x86_64-Intel-R-_Core-TM-_i7-3520M_CPU_@_2.90GHz-with-gentoo-2.2
KiB Mem:    16291304 total,   1754736 free
ld GNU ld (GNU Binutils) 2.23.1
app-shells/bash:          4.2_p45
dev-java/java-config:     2.1.12-r1
dev-lang/python:          2.7.5-r3, 3.2.5-r3, 3.3.3
dev-util/cmake:           2.8.11.2
sys-apps/baselayout:      2.2
sys-apps/openrc:          0.12.4
sys-apps/sandbox:         2.6-r1
sys-devel/autoconf:       2.13, 2.69
sys-devel/automake:       1.10.3, 1.11.6, 1.13.4, 1.14
sys-devel/binutils:       2.23.1
sys-devel/gcc:            4.4.7, 4.5.4, 4.7.3-r1
sys-devel/gcc-config:     1.7.3
sys-devel/libtool:        2.4.2
sys-devel/make:           3.82-r4
sys-kernel/linux-headers: 3.9 (virtual/os-headers)
sys-libs/glibc:           2.17
If you need I can try to create you relatively small chroot with this problem
reproduced, or point me and I'll try to do what I can. Unfortunately ATM I don't
understand this external linkage working.

Attachments:

3.go (856 bytes)

ianlancetaylor · 2013-12-13T20:39:42Z

Comment 4:

My guess is that gcc on this system defaults to -pie.
Can you run "go build -x 3.go" and show us the output?

gopherbot · 2013-12-14T08:00:14Z

Comment 5 by peter.volkov:

That's true, pie is enabled by default. It's not visible in the output though becase
it's defined in spec.
 $ go build -x 3.go
WORK=/tmp/go-build510371387
mkdir -p $WORK/command-line-arguments/_obj/
cd /tmp
/home/peter/projects/go/go/pkg/tool/linux_amd64/cgo -objdir
./go-build510371387/command-line-arguments/_obj/ -- -I
./go-build510371387/command-line-arguments/_obj/ 3.go
/home/peter/projects/go/go/pkg/tool/linux_amd64/6c -F -V -w -I
./go-build510371387/command-line-arguments/_obj/ -I
/home/peter/projects/go/go/pkg/linux_amd64 -o
./go-build510371387/command-line-arguments/_obj/_cgo_defun.6 -D GOOS_linux -D
GOARCH_amd64 ./go-build510371387/command-line-arguments/_obj/_cgo_defun.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fmessage-length=0 -print-libgcc-file-name
gcc -I . -g -O2 -fPIC -m64 -pthread -fmessage-length=0 -I
./go-build510371387/command-line-arguments/_obj/ -o
./go-build510371387/command-line-arguments/_obj/_cgo_main.o -c
./go-build510371387/command-line-arguments/_obj/_cgo_main.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fmessage-length=0 -I
./go-build510371387/command-line-arguments/_obj/ -o
./go-build510371387/command-line-arguments/_obj/_cgo_export.o -c
./go-build510371387/command-line-arguments/_obj/_cgo_export.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fmessage-length=0 -I
./go-build510371387/command-line-arguments/_obj/ -o
./go-build510371387/command-line-arguments/_obj/3.cgo2.o -c
./go-build510371387/command-line-arguments/_obj/3.cgo2.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fmessage-length=0 -o
./go-build510371387/command-line-arguments/_obj/_cgo_.o
./go-build510371387/command-line-arguments/_obj/_cgo_main.o
./go-build510371387/command-line-arguments/_obj/_cgo_export.o
./go-build510371387/command-line-arguments/_obj/3.cgo2.o
/home/peter/projects/go/go/pkg/tool/linux_amd64/cgo -objdir
./go-build510371387/command-line-arguments/_obj/ -dynimport
./go-build510371387/command-line-arguments/_obj/_cgo_.o -dynout
./go-build510371387/command-line-arguments/_obj/_cgo_import.c
/home/peter/projects/go/go/pkg/tool/linux_amd64/6c -F -V -w -I
./go-build510371387/command-line-arguments/_obj/ -I
/home/peter/projects/go/go/pkg/linux_amd64 -o
./go-build510371387/command-line-arguments/_obj/_cgo_import.6 -D GOOS_linux -D
GOARCH_amd64 ./go-build510371387/command-line-arguments/_obj/_cgo_import.c
gcc -I . -g -O2 -fPIC -m64 -pthread -fmessage-length=0 -o
./go-build510371387/command-line-arguments/_obj/_all.o
./go-build510371387/command-line-arguments/_obj/_cgo_export.o
./go-build510371387/command-line-arguments/_obj/3.cgo2.o -Wl,-r -nostdlib
/usr/lib/gcc/x86_64-pc-linux-gnu/4.7.3/libgcc.a
/home/peter/projects/go/go/pkg/tool/linux_amd64/6g -o
./go-build510371387/command-line-arguments/_obj/_go_.6 -p command-line-arguments -D
_/tmp -I ./go-build510371387
./go-build510371387/command-line-arguments/_obj/_cgo_gotypes.go
./go-build510371387/command-line-arguments/_obj/3.cgo1.go
/home/peter/projects/go/go/pkg/tool/linux_amd64/pack grcP ./go-build510371387
./go-build510371387/command-line-arguments.a
./go-build510371387/command-line-arguments/_obj/_go_.6
./go-build510371387/command-line-arguments/_obj/_cgo_import.6
./go-build510371387/command-line-arguments/_obj/_cgo_defun.6
./go-build510371387/command-line-arguments/_obj/_all.o
cd .
/home/peter/projects/go/go/pkg/tool/linux_amd64/6l -o 3 -L $WORK
$WORK/command-line-arguments.a
# command-line-arguments
/usr/lib/gcc/x86_64-pc-linux-gnu/4.7.3/../../../../x86_64-pc-linux-gnu/bin/ld:
/var/tmp/go-link-hxLIUS/go.o: relocation R_X86_64_32 against `type.*' can not be used
when making a shared object; recompile with -fPIC
/var/tmp/go-link-hxLIUS/go.o: could not read symbols: Bad value
collect2: error: ld returned 1 exit status
/home/peter/projects/go/go/pkg/tool/linux_amd64/6l: running gcc failed: unsuccessful
exit status 0x100

ianlancetaylor · 2013-12-14T16:35:27Z

Comment 6:

The Go linker does not currently support building objects that may be linked into a PIE.

Labels changed: added repo-main, release-none.

Status changed to Accepted.

gopherbot · 2014-01-05T13:51:15Z

Comment 7 by enigskai:

I have the same issue on a hardened Gentoo setup, where PIE/PIC are enabled by default. 
For those who are wondering, it is possible to work around this by disabling PIC when
building.
For example: go build -ldflags '-extldflags=-fno-PIC' 3.go

gopherbot · 2014-11-02T23:17:00Z

Comment 8 by SystmKor:

Has there been any progress with go working with all of the PaX features?

ianlancetaylor · 2014-11-02T23:20:55Z

Comment 9:

If you have questions about PaX in general, please ask on the mailing list
golang-nuts@googlegroups.com.
This particular issue is about generating code that can be linked into a PIE.  There has
been no progress on that.

gopherbot · 2014-11-02T23:34:13Z

Comment 10 by SystmKor:

I don't have questions about PaX in general. I have posted about this subject in the
mailing list https://groups.google.com/forum/#!topic/golang-nuts/Mie3Yfawksc.
I am curious about the timeline of having fully compatible PaX and go. If there is
something I can do to expedite this I would be happy to try and help.

minux · 2014-11-03T00:30:41Z

Comment 11:

As I said on the mailing list, PaX offers little benefit for Go.
If you system is running purely Go code, then even without PaX,
the system is still more secure than running C/C++ programs
with PaX.

ianlancetaylor · 2014-11-03T02:02:32Z

Comment 12:

Please let's take any discussions about PaX to the mailing list.
This issue is only about linker support for PIE, nothing else.

gopherbot · 2014-11-03T04:52:16Z

Comment 13 by SystmKor:

You are right about mailing list for now. I apologize. I guess I have inadvertently
derailed the comments farther than I intended. I wasn't trying to spark a discussion
about PaX but just curious about if it was going to be a thing.

gopherbot · 2014-11-03T04:52:51Z

Comment 14 by SystmKor:

You're right about moving this to the mailing list. I apologize. I guess I have
inadvertently derailed the comments farther than I intended. I wasn't trying to spark a
discussion about PaX but just curious about if it was going to be a thing.

mwhudson · 2015-07-16T21:50:10Z

Given we can build actual shared libraries out of Go code now, building pie executables shouldn't be that hard. I'm not sure what changes are required though.

mwhudson · 2016-03-31T21:36:20Z

-buildmode=pie is a thing now, so it would be possible to use that. OTOH, I don't actually understand what breaks when it is not used and the system linker assumes it by default...

mwhudson · 2016-04-26T01:30:59Z

I've just run into something similar, but I think this specific bug is closed. We even test cgo with -linkmode=external -extldflags "-pie" now.

These patches are for two issues: * Enabling Go to build on Alpine by disabling PIC per: golang/go#6940 https://github.com/docker-library/golang/blob/master/1.7/alpine/no-pic.patch * Fixing Go 1.4 bug appearing on macOS 10.12.1 per: golang/go#16352 (comment)

gopherbot added accepted labels Nov 3, 2014

rsc added this to the Unplanned milestone Apr 10, 2015

rsc removed release-none labels Apr 10, 2015

hyangah mentioned this issue May 13, 2015

build: run android builder with android-L devices. #10807

Closed

rsc changed the title ~~cmd/ld: support PIE when using the external linker~~ cmd/link: support PIE when using the external linker Jun 8, 2015

rsc modified the milestones: Go1.7Early, Unplanned Mar 3, 2016

ncopa mentioned this issue Mar 31, 2016

runtime: go 1.6 (linux/amd64) segfault with musl libc #14851

Closed

mwhudson closed this as completed Apr 26, 2016

clandmeter mentioned this issue Jul 7, 2016

testing/gogs: New version 0.9.13, that builds (on GCC 5.3.0) alpinelinux/aports#151

Closed

golang locked and limited conversation to collaborators Apr 26, 2017

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cmd/link: support PIE when using the external linker #6940

cmd/link: support PIE when using the external linker #6940

gopherbot commented Dec 12, 2013

minux commented Dec 13, 2013

minux commented Dec 13, 2013

gopherbot commented Dec 13, 2013

ianlancetaylor commented Dec 13, 2013

gopherbot commented Dec 14, 2013

ianlancetaylor commented Dec 14, 2013

gopherbot commented Jan 5, 2014

gopherbot commented Nov 2, 2014

ianlancetaylor commented Nov 2, 2014

gopherbot commented Nov 2, 2014

minux commented Nov 3, 2014

ianlancetaylor commented Nov 3, 2014

gopherbot commented Nov 3, 2014

gopherbot commented Nov 3, 2014

mwhudson commented Jul 16, 2015

mwhudson commented Mar 31, 2016

mwhudson commented Apr 26, 2016

cmd/link: support PIE when using the external linker #6940

cmd/link: support PIE when using the external linker #6940

Comments

gopherbot commented Dec 12, 2013

minux commented Dec 13, 2013

minux commented Dec 13, 2013

gopherbot commented Dec 13, 2013

ianlancetaylor commented Dec 13, 2013

gopherbot commented Dec 14, 2013

ianlancetaylor commented Dec 14, 2013

gopherbot commented Jan 5, 2014

gopherbot commented Nov 2, 2014

ianlancetaylor commented Nov 2, 2014

gopherbot commented Nov 2, 2014

minux commented Nov 3, 2014

ianlancetaylor commented Nov 3, 2014

gopherbot commented Nov 3, 2014

gopherbot commented Nov 3, 2014

mwhudson commented Jul 16, 2015

mwhudson commented Mar 31, 2016

mwhudson commented Apr 26, 2016