When a response file is in use, "$*" contains the response file and not
the parameters; both the linker and compiler wrappers are updated to use
the response-expanded params.
The compiler driver likes to pass parameters to the linker via a
response file, including -shared.
LLD rejects the combination of (-shared -pie), whereas other linkers
silently ignore the contradiction:
```
ld.lld: error: -shared and -pie may not be used together
```
This breaks certain configurations using LLD as a linker.
Changing `add-hardening.sh` results in a full rebuild. To avoid the
rebuild, here is a quick test case which shows the new hardening script
allows the link to succeed:
```
{ pkgs ? import <nixpkgs> {} }:
let
# gcc silently accepts -shared -pie together, lld does not.
linker = pkgs.wrapBintoolsWith { bintools = pkgs.llvmPackages.lld; };
patchWrapper = prev: prev.overrideAttrs (final: prev: let
prevScript = builtins.match (".*(/nix/store/[a-z0-9]+-add-hardening.sh).*") prev.postFixup;
in {
postFixup = (builtins.replaceStrings prevScript ["${./new-add-hardening.sh}"] prev.postFixup);
});
in
pkgs.stdenv.mkDerivation {
name = "nixpkgs-hardening-bug";
src = pkgs.writeText "src.c" "int main(int argc, char* argv[]) { return 0; }";
NIX_HARDENING_ENABLE = "pie";
unpackPhase = ":";
buildPhase = ''
$CC -c -o src.o $src
bash -x ${patchWrapper linker}/bin/ld.lld -o $out @${pkgs.writeText "responsefile" "-shared"} src.o
'';
}
```
Fixes: #178162
Signed-off-by: Peter Waller <p@pwaller.net>
LLD supports Windows-style linker arguments, but these previously
triggered purity check false positives, because it saw that they
started with a '/' and assumed they were paths.
This tweaks the path detection to allow through certain values that
could be paths, but are much more likely to be LINK.EXE-style flags.
The risk of false negatives here is low — the only things we'd now
fail to catch would be attempts to link with libraries in the root
directory, which doesn't happen in practice.
We also teach the wrapper how to apply its purity checks to library
paths specified with the /LIBPATH: option.
Tested that paths we expect to be rejected (like /lib/libfoo.so) still
are.
NixOS/nixpkgs#146275 has more discussion on this; the abridged version
is that `lld` defaults to using `--build-id=fast` while GNU `ld` defaults
to `--build-id=sha1`. These differ in length and so
`separate-debug-info.sh`, as of this writing, errors on `lld`'s shorter
`--build-id=fast`-generated hashes.
`lld` offers the following `build-id` styles:
- UUID (random; fast but bad for reproducibility)
- fast (xxhash; fast but shorter hashes)
- user provided hexstring
- SHA1
- MD5
GNU `ld` supports the latter three options, `mold` supports all of these
plus SHA256.
UUID is out because it's not reproducible, fast isn't supported by GNU
`ld`
Using a nix provided (sourced from the output base hash) hash as the
`build-id` seems tempting but would require a little extra work
(we have to include some characteristic of the binary being hashed
so that binaries within a derivation still have unique hashes; it
seems easy to get this wrong; i.e. a path based approach would make
two otherwise identical binaries that reside at different paths have
different `build-id` hashes)
That leaves SHA1 and MD5 and GNU `ld` already defaults to the former.
This commit adds `$NIX_BUILD_ID_STYLE` as an escape hatch, in case any
packages have strong opinions about which hash to use.
----
Note that if/when NixOS/nixpkgs#146275 goes through, this change can be
reverted if linker speed is a priority.
The motivation behind this is to alleviate the problem
described in https://github.com/NixOS/nixpkgs/issues/41340.
I'm not sure if this completely fixes the problem, but it
eliminates one more area where we can exceed command line
length limits.
This is essentially the same change as in #112449,
except for `ld-wrapper.sh` instead of `cc-wrapper.sh`.
However, that change alone was not enough; on macOS the
`ld` provided by `darwin.cctools` fails if you use process
substitution to generate the response file, so I put up a
PR to fix that:
https://github.com/tpoechtrager/cctools-port/pull/131
… and I included a patch referencing that fix so that the
new `ld-wrapper` still works on macOS.
not all linkers have a ld binary in bin
also note the '${ld:-}' which allows users to set the ld path with a env
var
> '${foo:-val}' $foo, or val if unset (or null)
For reasons explained in the commit contents, in order to build the
native gnat package for x86_64-darwin, the native gnatboot package for
x86_64-darwin must have access to both the Clang integrated assembler
and the cctools GNU assembler for that platform. This commit creates a
package with both of those assemblers that x86_64-darwin gnatboot can
then be wrapped with.
Co-authored-by: Robin Gloster <mail@glob.in>
stdenv: print message if structuredAttrs is enabled
stdenv: add _append
reduces the chance of a user doing it wrong
fix nix develop issue
output hooks don't work yet in nix develop though
making $outputs be the same on non-structuredAttrs and structuredAttrs
is too much trouble.
lets instead make a function that gets the output names
reading environment file '/nix/store/2x7m69a2sm2kh0r6v0q5s9z1dh41m4xf-xz-5.2.5-env-bin'
nix: src/nix/develop.cc:299: std::string Common::makeRcScript(nix::ref<nix::Store>, const BuildEnvironment&, const Path&): Assertion `outputs != buildEnvironment.vars.end()' failed.
use a function to get all output names instead of using $outputs
copy env functionality from https://github.com/NixOS/nixpkgs/pull/76732/commits
`exit -1` is equivalent to `exit 255`, since Bash does modulo 256 on the
number.
As per ShellCheck:
> SC2242 (error): Can only exit with status 0-255. Other data should be
> written to stdout/stderr.
POSIX sh (and `bash`) impose a restriction on environment variable name
format and disallow hypheps in the names. Normally it's not a problem
as nothing usually tries to refer nyphenated names.
One exception is `nix develop` (https://github.com/NixOS/nix/issues/6848):
$ nix develop -f. gcc -L
gcc-wrapper> ...-get-env.sh: line 70: expand-response-params: bad substitution
Note that bash usually uses explicitly created `expandResponseParams`
variant of the same variable.
To work the problem around let's avoid environment variable export and move
it to `passthru` for `cc` (used ina few places) and remove it completely for
`binutils` (does not seem to be used at all).
Without this change cross-built gcc fails to detect stack protector style:
$ nix log -f pkgs/stdenv/linux/make-bootstrap-tools-cross.nix powerpc64le.bootGCC | fgrep __stack_chk_fail
checking __stack_chk_fail in target C library... no
checking __stack_chk_fail in target C library... no
It happens because gcc treats search paths differently:
https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/configure.ac;h=446747311a6aec3c810ad6aa4190f7bd383b94f7;hb=HEAD#l2458
if test x$host != x$target || test "x$TARGET_SYSTEM_ROOT" != x ||
test x$build != x$host || test "x$with_build_sysroot" != x; then
...
if test "x$with_build_sysroot" != "x"; then
target_header_dir="${with_build_sysroot}${native_system_header_dir}"
elif test "x$with_sysroot" = x; then
target_header_dir="${test_exec_prefix}/${target_noncanonical}/sys-include"
elif test "x$with_sysroot" = xyes; then
target_header_dir="${test_exec_prefix}/${target_noncanonical}/sys-root${native_system_header_dir}"
else
target_header_dir="${with_sysroot}${native_system_header_dir}"
fi
else
target_header_dir=${native_system_header_dir}
fi
By passing --with-build-sysroot=/ we trick cross-case to use
`target_header_dir="${with_sysroot}${native_system_header_dir}"`
which makes it equivalent to non-cross
`target_header_dir="${with_build_sysroot}${native_system_header_dir}"`
Tested the following setups:
- cross-compiler without libc headers (powerpc64le-static)
- cross-compiler with libc headers (powerpc64le-debug)
- cross-build compiler with libc headers (powerpc64le bootstrapTools)
Before the change only 2 of 3 compilers detected libc headers.
After the change all 3 compilers detected libc headers.
For darwin we silently ignore '-syslibroot //' argument as it does not
introduce impurities.
While at it dropped mingw special case for no-libc build. Before the change
we passed both '--without-headers --with-native-system-headers-dir' for
no-libc gcc-static builds. This tricked darwin builds to find sys/sdt.h
and fail inhibid_libc builds. Now all targets avoid passing native headers
for gcc-static builds.
While at it fixed correct headers passing to
--with-native-system-headers-dir= in host != target case: we were passing
host's headers where intention was to pass target's headers.
Noticed the mismatch as a build failure on pkgsCross.powernv.stdenv.cc
on darwin where `sys/sdt.h` is present in host's headers (libSystem)
but not target's headers (`glibc`).
Co-authored-by: Adam Joseph <54836058+amjoseph-nixpkgs@users.noreply.github.com>
this shouldn't change any binary available in the default build environment
because bintools-unwrapped is already in path ( idk where it comes from but i know because objcopy is in path but not in the wrapper )
this just makes all the binaries available under 'bintools' instead of
having to use 'bintools-unwrapped'
reduces confusion because now 'objcopy' and others will be in 'bintools'
As far as I can tell, this has never actually done anything, as
LDEMULATION is not exported. I tried exporting it and builds broke,
and as it doesn't seem to have caused any problems as a noop all these
years it didn't seem worth investigating further.
So far we've ignored response files in arguments, and did not
check linkType against expanded parameters. This means if
we have `-static` in a @reponse-file, linkType will not be
set to `-static` as we never check against the expanded arguments
from response files.
fixes e.g.:
pkgsMusl.libfsm
pkgsMusl.libiscsi
pkgsMusl.nsjail
pkgsMusl.pv
match strings have whitespace on either side, which wasn't
matching leading/trailing arguments previously
`--enable-deterministic-archives` is a GNU specific strip flag and
causes other strip implementations (for example LLVM's, see #138013)
to fail. Since strip failures are ignored, this means that stripping
doesn't work at all in certain situation (causing unnecessary
dependencies etc.).
To fix this, no longer pass `--enable-deterministic-archives`
unconditionally, but instead add it in a GNU binutils specific strip
wrapper only.
`commonStripFlags` was only used for this flag, so we can remove
it altogether.
Future work could be to make a generic strip wrapper, with support for
nix-support/strip-flags-{before,after} and NIX_STRIP_FLAGS_{BEFORE,AFTER}.
This possibly overkill and unnecessary though -- also with the
additional challenge of incorporating the darwin strip wrapper somehow.
