glibc: allow to build position-independent static executable #123989
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Also @Ericson2314 claims static-pie support, it is not quite true yet: https://news.ycombinator.com/item?id=23657020 #include <stdio.h>
int main() {
printf("main: %p\n", main);
return 0;
}with import <nixpkgs> {};
stdenv.mkDerivation {
name = "env";
nativeBuildInputs = [
bashInteractive
];
buildInputs = [
glibc.static
];
}$ gcc -static-pie -o main main.c
$ gdb ./main
Reading symbols from ./main...
(gdb) r
Starting program: /tmp/tmp.kSRlP5T372/solo5/main
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7f5115c in __dcigettext ()
(gdb) bt
#0 0x00007ffff7f5115c in __dcigettext ()
#1 0x00007ffff7f502ce in __assert_fail ()
#2 0x00007ffff7f90415 in _dl_relocate_static_pie ()
#3 0x00007ffff7f4f3b8 in __libc_start_main ()
#4 0x00007ffff7f4ee1a in _start () at ../sysdeps/x86_64/start.S:120 |
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My blind guess is, that it somehow breaks TLS: |
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This works in an archlinux container. So it is something that breaks in our setup. |
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This is what archlinux produces: This is Nixpkgs: |
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Interesting enough even without the change glibc already builds |
8 tasks
This enables ALSR on static executables, which makes them harder to exploit by providing a crt suitable for static PIEs. Does this break existing binaries? Likely not. Static-pie is only used if explicitly enabled.
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Ha! It works now. After compiling glibc from source I could pin-point the assertion that broke the execution. |
Mic92
commented
May 22, 2021
Mic92
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May 22, 2021
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Ericson2314
reviewed
May 24, 2021
Ericson2314
approved these changes
May 24, 2021
Co-authored-by: John Ericson <git@JohnEricson.me>
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Someone tested also macOS/clang for me. Good to go. |
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I think this change broke glibc on armv7l: According to https://sourceware.org/glibc/wiki/PortStatus
On Debian and Gentoo Reverting 61c74e1 (on top of 59ef808) allowed me to successfully build glibc on armv7l. |
Mic92
commented
Jul 1, 2021
| @@ -153,6 +153,8 @@ stdenv.mkDerivation ({ | |||
| "--enable-add-ons" | |||
| "--sysconfdir=/etc" | |||
| "--enable-stackguard-randomization" | |||
| "--enable-static-pie" | |||
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Well I guess this line should be disabled on arm-legacy again than.
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This enables ALSR on static executables, which makes them harder to
exploit by providing a crt suitable for static PIEs.
Motivation for this change
Things done
sandboxinnix.confon non-NixOS linux)nix-shell -p nixpkgs-review --run "nixpkgs-review wip"./result/bin/)