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Date: Tue, 25 Aug 2020 12:52:12 +0200
From: Harald Hoyer <harald@...hat.com>
To: musl@...ts.openwall.com
Subject: Re: [PATCH] Enable linking to a static position independent
executable
Am 27.04.20 um 14:32 schrieb harald@...hat.com:
> From: Harald Hoyer <harald@...hat.com>
>
> This also enables address space layout randomization (ASLR).
>
> $ cat hello.c
>
> int main()
> {
> printf("main = 0x%lxd\n", main);
> return 0;
> }
>
> $ gcc -fPIE -static-pie -o hello hello.c -specs musl-gcc.specs
>
> $ ldd hello
> statically linked
>
> $ file hello
> hello: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), statically linked, with debug_info, not stripped, too many notes (256)
>
> $ ./hello
> main = 0x7f858c4e72b9d
>
> $ ./hello
> main = 0x7f0854d312b9d
>
> $ ./hello
> main = 0x7f7179a1d2b9d
>
> $ ./hello
> main = 0x7f37f981b2b9d
>
> $ readelf -l hello
>
> Elf file type is DYN (Shared object file)
> Entry point 0x104f
> There are 7 program headers, starting at offset 64
>
> Program Headers:
> Type Offset VirtAddr PhysAddr
> FileSiz MemSiz Flags Align
> LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000
> 0x0000000000000308 0x0000000000000308 R 0x1000
> LOAD 0x0000000000001000 0x0000000000001000 0x0000000000001000
> 0x0000000000003eb7 0x0000000000003eb7 R E 0x1000
> LOAD 0x0000000000005000 0x0000000000005000 0x0000000000005000
> 0x000000000000136c 0x000000000000136c R 0x1000
> LOAD 0x0000000000006e50 0x0000000000007e50 0x0000000000007e50
> 0x00000000000002e0 0x00000000000009a0 RW 0x1000
> DYNAMIC 0x0000000000006e70 0x0000000000007e70 0x0000000000007e70
> 0x0000000000000180 0x0000000000000180 RW 0x8
> GNU_STACK 0x0000000000000000 0x0000000000000000 0x0000000000000000
> 0x0000000000000000 0x0000000000000000 RW 0x10
> GNU_RELRO 0x0000000000006e50 0x0000000000007e50 0x0000000000007e50
> 0x00000000000001b0 0x00000000000001b0 R 0x1
>
> Section to Segment mapping:
> Segment Sections...
> 00 .hash .gnu.hash .dynsym .dynstr .rela.dyn
> 01 .init .plt .text .fini
> 02 .rodata .eh_frame
> 03 .init_array .fini_array .data.rel.ro .dynamic .got .got.plt .data .bss
> 04 .dynamic
> 05
> 06 .init_array .fini_array .data.rel.ro .dynamic .got
> ---
> 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:
>
>
Anythink missing? Does it need more work?
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