lix-releng-staging/flake.nix
Maximilian Bosch 045ee37438 libstore/local-derivation-goal: prohibit creating setuid/setgid binaries
With Linux kernel >=6.6 & glibc 2.39 a `fchmodat2(2)` is available that
isn't filtered away by the libseccomp sandbox.

Being able to use this to bypass that restriction has surprising results
for some builds such as lxc[1]:

> With kernel ≥6.6 and glibc 2.39, lxc's install phase uses fchmodat2,
> which slips through 9b88e52846/src/libstore/build/local-derivation-goal.cc (L1650-L1663).
> The fixupPhase then uses fchmodat, which fails.
> With older kernel or glibc, setting the suid bit fails in the
> install phase, which is not treated as fatal, and then the
> fixup phase does not try to set it again.

Please note that there are still ways to bypass this sandbox[2] and this is
mostly a fix for the breaking builds.

This change works by creating a syscall filter for the `fchmodat2`
syscall (number 452 on most systems). The problem is that glibc 2.39
is needed to have the correct syscall number available via
`__NR_fchmodat2` / `__SNR_fchmodat2`, but this flake is still on
nixpkgs 23.11. To have this change everywhere and not dependent on the
glibc this package is built against, I added a header
"fchmodat2-compat.hh" that sets the syscall number based on the
architecture. On most platforms its 452 according to glibc with a few
exceptions:

    $ rg --pcre2 'define __NR_fchmodat2 (?!452)'
    sysdeps/unix/sysv/linux/x86_64/x32/arch-syscall.h
    58:#define __NR_fchmodat2 1073742276

    sysdeps/unix/sysv/linux/mips/mips64/n32/arch-syscall.h
    67:#define __NR_fchmodat2 6452

    sysdeps/unix/sysv/linux/mips/mips64/n64/arch-syscall.h
    62:#define __NR_fchmodat2 5452

    sysdeps/unix/sysv/linux/mips/mips32/arch-syscall.h
    70:#define __NR_fchmodat2 4452

    sysdeps/unix/sysv/linux/alpha/arch-syscall.h
    59:#define __NR_fchmodat2 562

I added a small regression-test to the setuid integration-test that
attempts to set the suid bit on a file using the fchmodat2 syscall.
I confirmed that the test fails without the change in
local-derivation-goal.

Additionally, we require libseccomp 2.5.5 or greater now: as it turns
out, libseccomp maintains an internal syscall table and
validates each rule against it. This means that when using libseccomp
2.5.4 or older, one may pass `452` as syscall number against it, but
since it doesn't exist in the internal structure, `libseccomp` will refuse
to create a filter for that. This happens with nixpkgs-23.11, i.e. on
stable NixOS and when building Lix against the project's flake.

To work around that

* a backport of libseccomp 2.5.5 on upstream nixpkgs has been
  scheduled[3].

* the package now uses libseccomp 2.5.5 on its own already. This is to
  provide a quick fix since the correct fix for 23.11 is still a staging cycle
  away.

We still need the compat header though since `SCMP_SYS(fchmodat2)`
internally transforms this into `__SNR_fchmodat2` which points to
`__NR_fchmodat2` from glibc 2.39, so it wouldn't build on glibc 2.38.
The updated syscall table from libseccomp 2.5.5 is NOT used for that
step, but used later, so we need both, our compat header and their
syscall table 🤷

Relevant PRs in CppNix:

* https://github.com/NixOS/nix/pull/10591
* https://github.com/NixOS/nix/pull/10501

[1] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2031073804
[2] https://github.com/NixOS/nixpkgs/issues/300635#issuecomment-2030844251
[3] https://github.com/NixOS/nixpkgs/pull/306070

(cherry picked from commit ba6804518772e6afb403dd55478365d4b863c854)
Change-Id: I6921ab5a363188c6bff617750d00bb517276b7fe
2024-05-03 16:29:06 +02:00

506 lines
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{
description = "The purely functional package manager";
inputs = {
nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11-small";
nixpkgs-regression.url = "github:NixOS/nixpkgs/215d4d0fd80ca5163643b03a33fde804a29cc1e2";
pre-commit-hooks = {
url = "github:cachix/git-hooks.nix";
flake = false;
};
flake-compat = {
url = "github:edolstra/flake-compat";
flake = false;
};
};
outputs =
{
self,
nixpkgs,
nixpkgs-regression,
pre-commit-hooks,
flake-compat,
}:
let
inherit (nixpkgs) lib;
officialRelease = false;
# Set to true to build the release notes for the next release.
buildUnreleasedNotes = false;
version = lib.fileContents ./.version + versionSuffix;
versionSuffix =
if officialRelease then
""
else
"pre${
builtins.substring 0 8 (self.lastModifiedDate or self.lastModified or "19700101")
}_${self.shortRev or "dirty"}";
linux32BitSystems = [ "i686-linux" ];
linux64BitSystems = [
"x86_64-linux"
"aarch64-linux"
];
linuxSystems = linux32BitSystems ++ linux64BitSystems;
darwinSystems = [
"x86_64-darwin"
"aarch64-darwin"
];
systems = linuxSystems ++ darwinSystems;
crossSystems = [
"armv6l-linux"
"armv7l-linux"
"x86_64-freebsd13"
"x86_64-netbsd"
];
stdenvs = [
"gccStdenv"
"clangStdenv"
"stdenv"
"libcxxStdenv"
"ccacheStdenv"
];
forAllSystems = lib.genAttrs systems;
forAllCrossSystems = lib.genAttrs crossSystems;
forAllStdenvs =
f:
lib.listToAttrs (
map (stdenvName: {
name = "${stdenvName}Packages";
value = f stdenvName;
}) stdenvs
);
# Memoize nixpkgs for different platforms for efficiency.
nixpkgsFor = forAllSystems (
system:
let
make-pkgs =
crossSystem: stdenv:
import nixpkgs {
localSystem = {
inherit system;
};
crossSystem =
if crossSystem == null then
null
else
{
system = crossSystem;
}
// lib.optionalAttrs (crossSystem == "x86_64-freebsd13") { useLLVM = true; };
overlays = [
(overlayFor (p: p.${stdenv}))
(final: prev: { nixfmt = final.callPackage ./nix-support/nixfmt.nix { }; })
];
config.permittedInsecurePackages = [ "nix-2.13.6" ];
};
stdenvs = forAllStdenvs (make-pkgs null);
native = stdenvs.stdenvPackages;
in
{
inherit stdenvs native;
static = native.pkgsStatic;
cross = forAllCrossSystems (crossSystem: make-pkgs crossSystem "stdenv");
}
);
binaryTarball =
nix: pkgs: pkgs.callPackage ./nix-support/binary-tarball.nix { inherit nix version; };
overlayFor =
getStdenv: final: prev:
let
currentStdenv = getStdenv final;
in
{
nixStable = prev.nix;
# Forward from the previous stage as we dont want it to pick the lowdown override
nixUnstable = prev.nixUnstable;
build-release-notes = final.buildPackages.callPackage ./maintainers/build-release-notes.nix { };
check-headers = final.buildPackages.callPackage ./maintainers/check-headers.nix { };
clangbuildanalyzer = final.buildPackages.callPackage ./misc/clangbuildanalyzer.nix { };
default-busybox-sandbox-shell = final.busybox.override {
useMusl = true;
enableStatic = true;
enableMinimal = true;
extraConfig = ''
CONFIG_FEATURE_FANCY_ECHO y
CONFIG_FEATURE_SH_MATH y
CONFIG_FEATURE_SH_MATH_64 y
CONFIG_ASH y
CONFIG_ASH_OPTIMIZE_FOR_SIZE y
CONFIG_ASH_ALIAS y
CONFIG_ASH_BASH_COMPAT y
CONFIG_ASH_CMDCMD y
CONFIG_ASH_ECHO y
CONFIG_ASH_GETOPTS y
CONFIG_ASH_INTERNAL_GLOB y
CONFIG_ASH_JOB_CONTROL y
CONFIG_ASH_PRINTF y
CONFIG_ASH_TEST y
'';
};
nix = final.callPackage ./package.nix {
inherit versionSuffix;
stdenv = currentStdenv;
busybox-sandbox-shell = final.busybox-sandbox-shell or final.default-busybox-sandbox-shell;
};
# Export the patched version of boehmgc & libseccomp that Lix uses into the overlay
# for consumers of this flake.
boehmgc-nix = final.nix.boehmgc-nix;
libseccomp-nix = final.nix.libseccomp-nix;
};
in
{
# A Nixpkgs overlay that overrides the 'nix' and
# 'nix.perl-bindings' packages.
overlays.default = overlayFor (p: p.stdenv);
hydraJobs = {
# Binary package for various platforms.
build = forAllSystems (system: self.packages.${system}.nix);
rl-next = forAllSystems (
system:
let
rl-next-check =
name: dir:
let
pkgs = nixpkgsFor.${system}.native;
in
pkgs.buildPackages.runCommand "test-${name}-release-notes" { } ''
LANG=C.UTF-8 ${lib.getExe pkgs.build-release-notes} ${dir} >$out
'';
in
{
user = rl-next-check "rl-next" ./doc/manual/rl-next;
dev = rl-next-check "rl-next-dev" ./doc/manual/rl-next-dev;
}
);
# Perl bindings for various platforms.
perlBindings = forAllSystems (system: nixpkgsFor.${system}.native.nix.perl-bindings);
# Binary tarball for various platforms, containing a Nix store
# with the closure of 'nix' package.
binaryTarball = forAllSystems (
system: binaryTarball nixpkgsFor.${system}.native.nix nixpkgsFor.${system}.native
);
# docker image with Nix inside
dockerImage = lib.genAttrs linux64BitSystems (system: self.packages.${system}.dockerImage);
# API docs for Nix's unstable internal C++ interfaces.
internal-api-docs =
let
nixpkgs = nixpkgsFor.x86_64-linux.native;
inherit (nixpkgs) pkgs;
nix = pkgs.callPackage ./package.nix {
inherit versionSuffix officialRelease buildUnreleasedNotes;
inherit (pkgs) build-release-notes;
internalApiDocs = true;
busybox-sandbox-shell = pkgs.busybox-sandbox-shell;
};
in
nix.overrideAttrs (prev: {
# This Hydra job is just for the internal API docs.
# We don't need the build artifacts here.
dontBuild = true;
doCheck = false;
doInstallCheck = false;
});
# System tests.
tests = import ./tests/nixos { inherit lib nixpkgs nixpkgsFor; } // {
# Make sure that nix-env still produces the exact same result
# on a particular version of Nixpkgs.
evalNixpkgs =
with nixpkgsFor.x86_64-linux.native;
runCommand "eval-nixos" { buildInputs = [ nix ]; } ''
type -p nix-env
# Note: we're filtering out nixos-install-tools because https://github.com/NixOS/nixpkgs/pull/153594#issuecomment-1020530593.
time nix-env --store dummy:// -f ${nixpkgs-regression} -qaP --drv-path | sort | grep -v nixos-install-tools > packages
[[ $(sha1sum < packages | cut -c1-40) = 402242fca90874112b34718b8199d844e8b03d12 ]]
mkdir $out
'';
nixpkgsLibTests = forAllSystems (
system:
import (nixpkgs + "/lib/tests/release.nix") {
pkgs = nixpkgsFor.${system}.native;
nixVersions = [ self.packages.${system}.nix ];
}
);
};
pre-commit = forAllSystems (
system:
let
pkgs = nixpkgsFor.${system}.native;
# Import pre-commit bypassing the flake because flakes don't let
# you have overlays. Also their implementation forces an
# unnecessary reimport of nixpkgs for our use cases.
tools = import (pre-commit-hooks + "/nix/call-tools.nix") pkgs;
pre-commit-run = pkgs.callPackage (pre-commit-hooks + "/nix/run.nix") {
inherit tools;
isFlakes = true;
# unused!
gitignore-nix-src = builtins.throw "gitignore-nix-src is unused";
};
in
pre-commit-run {
src = self;
hooks = {
no-commit-to-branch = {
enable = true;
settings.branch = [ "main" ];
};
check-case-conflicts.enable = true;
check-executables-have-shebangs = {
enable = true;
stages = [ "commit" ];
};
check-shebang-scripts-are-executable = {
enable = true;
stages = [ "commit" ];
};
check-symlinks = {
enable = true;
excludes = [ "^tests/functional/lang/symlink-resolution/broken$" ];
};
check-merge-conflicts.enable = true;
end-of-file-fixer = {
enable = true;
excludes = [
"\\.drv$"
"^tests/functional/lang/"
];
};
mixed-line-endings = {
enable = true;
excludes = [ "^tests/functional/lang/" ];
};
release-notes = {
enable = true;
package = pkgs.build-release-notes;
files = "^doc/manual/rl-next(-dev)?";
pass_filenames = false;
entry = ''
${lib.getExe pkgs.build-release-notes} doc/manual/rl-next doc/manual/rl-next-dev
'';
};
check-headers = {
enable = true;
package = pkgs.check-headers;
files = "^src/";
types = [
"c++"
"file"
"header"
];
# generated files; these will never actually be seen by this
# check, and are left here as documentation
excludes = [
"(parser|lexer)-tab\\.hh$"
"\\.gen\\.hh$"
];
entry = lib.getExe pkgs.check-headers;
};
# TODO: Once the test suite is nicer, clean up and start
# enforcing trailing whitespace on tests that don't explicitly
# check for it.
trim-trailing-whitespace = {
enable = true;
stages = [ "commit" ];
excludes = [ "^tests/functional/lang/" ];
};
treefmt = {
enable = true;
settings.formatters = [ pkgs.nixfmt ];
};
};
}
);
};
# NOTE *do not* add fresh derivations to checks, always add them to
# hydraJobs first (so CI will pick them up) and only link them here
checks = forAllSystems (
system:
{
binaryTarball = self.hydraJobs.binaryTarball.${system};
perlBindings = self.hydraJobs.perlBindings.${system};
nixpkgsLibTests = self.hydraJobs.tests.nixpkgsLibTests.${system};
rl-next = self.hydraJobs.rl-next.${system}.user;
rl-next-dev = self.hydraJobs.rl-next.${system}.dev;
pre-commit = self.hydraJobs.pre-commit.${system};
}
// (lib.optionalAttrs (builtins.elem system linux64BitSystems)) {
dockerImage = self.hydraJobs.dockerImage.${system};
}
);
packages = forAllSystems (
system:
rec {
inherit (nixpkgsFor.${system}.native) nix;
default = nix;
}
// (
lib.optionalAttrs (builtins.elem system linux64BitSystems) {
nix-static = nixpkgsFor.${system}.static.nix;
dockerImage =
let
pkgs = nixpkgsFor.${system}.native;
image = import ./docker.nix {
inherit pkgs;
tag = version;
};
in
pkgs.runCommand "docker-image-tarball-${version}"
{ meta.description = "Docker image with Nix for ${system}"; }
''
mkdir -p $out/nix-support
image=$out/image.tar.gz
ln -s ${image} $image
echo "file binary-dist $image" >> $out/nix-support/hydra-build-products
'';
}
// builtins.listToAttrs (
map (crossSystem: {
name = "nix-${crossSystem}";
value = nixpkgsFor.${system}.cross.${crossSystem}.nix;
}) crossSystems
)
// builtins.listToAttrs (
map (stdenvName: {
name = "nix-${stdenvName}";
value = nixpkgsFor.${system}.stdenvs."${stdenvName}Packages".nix;
}) stdenvs
)
)
);
devShells =
let
makeShell =
pkgs: stdenv:
let
nix = pkgs.callPackage ./package.nix {
inherit stdenv versionSuffix;
busybox-sandbox-shell = pkgs.busybox-sandbox-shell or pkgs.default-busybox-sandbox;
forDevShell = true;
};
pre-commit = self.hydraJobs.pre-commit.${pkgs.system} or { };
in
(nix.override {
buildUnreleasedNotes = true;
officialRelease = false;
}).overrideAttrs
(
prev:
{
# Required for clang-tidy checks
buildInputs =
prev.buildInputs
++ [
pkgs.just
pkgs.nixfmt
]
++ lib.optional (pre-commit ? enabledPackages) pre-commit.enabledPackages
++ lib.optionals (stdenv.cc.isClang) [
pkgs.llvmPackages.llvm
pkgs.llvmPackages.clang-unwrapped.dev
];
nativeBuildInputs =
prev.nativeBuildInputs
++ lib.optional (stdenv.cc.isClang && !stdenv.buildPlatform.isDarwin) pkgs.buildPackages.bear
# Required for clang-tidy checks
++ lib.optionals (stdenv.cc.isClang) [
pkgs.buildPackages.cmake
pkgs.buildPackages.ninja
pkgs.buildPackages.llvmPackages.llvm.dev
]
++
lib.optional (stdenv.cc.isClang && stdenv.hostPlatform == stdenv.buildPlatform)
# for some reason that seems accidental and was changed in
# NixOS 24.05-pre, clang-tools is pinned to LLVM 14 when
# default LLVM is newer.
(pkgs.buildPackages.clang-tools.override { inherit (pkgs.buildPackages) llvmPackages; })
++ [
# FIXME(Qyriad): remove once the migration to Meson is complete.
pkgs.buildPackages.meson
pkgs.buildPackages.ninja
pkgs.buildPackages.cmake
pkgs.buildPackages.clangbuildanalyzer
];
src = null;
installFlags = "sysconfdir=$(out)/etc";
strictDeps = false;
shellHook = ''
PATH=$prefix/bin:$PATH
unset PYTHONPATH
export MANPATH=$out/share/man:$MANPATH
# Make bash completion work.
XDG_DATA_DIRS+=:$out/share
${lib.optionalString (pre-commit ? shellHook) pre-commit.shellHook}
'';
}
// lib.optionalAttrs (stdenv.buildPlatform.isLinux && pkgs.glibcLocales != null) {
# Required to make non-NixOS Linux not complain about missing locale files during configure in a dev shell
LOCALE_ARCHIVE = "${lib.getLib pkgs.glibcLocales}/lib/locale/locale-archive";
}
);
in
forAllSystems (
system:
let
makeShells =
prefix: pkgs:
lib.mapAttrs' (k: v: lib.nameValuePair "${prefix}-${k}" v) (
forAllStdenvs (stdenvName: makeShell pkgs pkgs.${stdenvName})
);
in
(makeShells "native" nixpkgsFor.${system}.native)
// (makeShells "static" nixpkgsFor.${system}.static)
// (forAllCrossSystems (
crossSystem:
let
pkgs = nixpkgsFor.${system}.cross.${crossSystem};
in
makeShell pkgs pkgs.stdenv
))
// {
default = self.devShells.${system}.native-stdenvPackages;
}
);
};
}