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|
# Verify that Linux builds cannot create setuid or setgid binaries.
{ lib, config, nixpkgs, ... }:
let
pkgs = config.nodes.machine.nixpkgs.pkgs;
fchmodat2-builder = pkgs.runCommandCC "fchmodat2-suid" {
passAsFile = [ "code" ];
code = builtins.readFile ./fchmodat2-suid.c;
# Doesn't work with -O0, shuts up the warning about that.
hardeningDisable = [ "fortify" ];
} ''
mkdir -p $out/bin/
$CC -x c "$codePath" -O0 -g -o $out/bin/fchmodat2-suid
'';
in
{
name = "setuid";
nodes.machine =
{ config, lib, pkgs, ... }:
{ virtualisation.writableStore = true;
nix.settings.substituters = lib.mkForce [ ];
nix.nixPath = [ "nixpkgs=${lib.cleanSource pkgs.path}" ];
virtualisation.additionalPaths = [
pkgs.stdenvNoCC
pkgs.pkgsi686Linux.stdenvNoCC
fchmodat2-builder
];
# need at least 6.6 to test for fchmodat2
boot.kernelPackages = pkgs.linuxKernel.packages.linux_6_6;
};
testScript = { nodes }: ''
# fmt: off
start_all()
with subtest("fchmodat2 suid regression test"):
machine.succeed("""
nix-build -E '(with import <nixpkgs> {}; runCommand "fchmodat2-suid" {
BUILDER = builtins.storePath ${fchmodat2-builder};
} "
exec \\"$BUILDER\\"/bin/fchmodat2-suid
")'
""")
# Copying to /tmp should succeed.
machine.succeed(r"""
nix-build --no-sandbox -E '(with import <nixpkgs> {}; runCommand "foo" {} "
mkdir -p $out
cp ${pkgs.coreutils}/bin/id /tmp/id
")'
""".strip())
machine.succeed('[[ $(stat -c %a /tmp/id) = 555 ]]')
machine.succeed("rm /tmp/id")
# Creating a setuid binary should fail.
machine.fail(r"""
nix-build --no-sandbox -E '(with import <nixpkgs> {}; runCommand "foo" {} "
mkdir -p $out
cp ${pkgs.coreutils}/bin/id /tmp/id
chmod 4755 /tmp/id
")'
""".strip())
machine.succeed('[[ $(stat -c %a /tmp/id) = 555 ]]')
machine.succeed("rm /tmp/id")
# Creating a setgid binary should fail.
machine.fail(r"""
nix-build --no-sandbox -E '(with import <nixpkgs> {}; runCommand "foo" {} "
mkdir -p $out
cp ${pkgs.coreutils}/bin/id /tmp/id
chmod 2755 /tmp/id
")'
""".strip())
machine.succeed('[[ $(stat -c %a /tmp/id) = 555 ]]')
machine.succeed("rm /tmp/id")
# The checks should also work on 32-bit binaries.
machine.fail(r"""
nix-build --no-sandbox -E '(with import <nixpkgs> { system = "i686-linux"; }; runCommand "foo" {} "
mkdir -p $out
cp ${pkgs.coreutils}/bin/id /tmp/id
chmod 2755 /tmp/id
")'
""".strip())
machine.succeed('[[ $(stat -c %a /tmp/id) = 555 ]]')
machine.succeed("rm /tmp/id")
# The tests above use fchmodat(). Test chmod() as well.
machine.succeed(r"""
nix-build --no-sandbox -E '(with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ perl ]; } "
mkdir -p $out
cp ${pkgs.coreutils}/bin/id /tmp/id
perl -e \"chmod 0666, qw(/tmp/id) or die\"
")'
""".strip())
machine.succeed('[[ $(stat -c %a /tmp/id) = 666 ]]')
machine.succeed("rm /tmp/id")
machine.fail(r"""
nix-build --no-sandbox -E '(with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ perl ]; } "
mkdir -p $out
cp ${pkgs.coreutils}/bin/id /tmp/id
perl -e \"chmod 04755, qw(/tmp/id) or die\"
")'
""".strip())
machine.succeed('[[ $(stat -c %a /tmp/id) = 555 ]]')
machine.succeed("rm /tmp/id")
# And test fchmod().
machine.succeed(r"""
nix-build --no-sandbox -E '(with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ perl ]; } "
mkdir -p $out
cp ${pkgs.coreutils}/bin/id /tmp/id
perl -e \"my \\\$x; open \\\$x, qw(/tmp/id); chmod 01750, \\\$x or die\"
")'
""".strip())
machine.succeed('[[ $(stat -c %a /tmp/id) = 1750 ]]')
machine.succeed("rm /tmp/id")
machine.fail(r"""
nix-build --no-sandbox -E '(with import <nixpkgs> {}; runCommand "foo" { buildInputs = [ perl ]; } "
mkdir -p $out
cp ${pkgs.coreutils}/bin/id /tmp/id
perl -e \"my \\\$x; open \\\$x, qw(/tmp/id); chmod 04777, \\\$x or die\"
")'
""".strip())
machine.succeed('[[ $(stat -c %a /tmp/id) = 555 ]]')
machine.succeed("rm /tmp/id")
'';
}
|
