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Date: Mon, 27 Apr 2020 14:32:07 +0200
From: harald@...hat.com
To: musl@...ts.openwall.com
Cc: Harald Hoyer <harald@...hat.com>
Subject: [PATCH] Enable linking to a static position independent executable
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:
--
2.26.2
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