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nixos/binfmt: Avoid adding to extra-sandbox-paths with fixBinary #494593

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Merged
dramforever merged 2 commits into from
Mar 2, 2026
+21 −4
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nixos/binfmt: Avoid adding to extra-sandbox-paths with fixBinary #494593

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0de75c6
nixos/binfmt: Avoid adding to extra-sandbox-paths with fixBinary
dramforever Feb 26, 2026
d312012
nixos/tests/systemd-binfmt: chroot: Assert extra-sandbox-path == []
dramforever Feb 26, 2026
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11 changes: 8 additions & 3 deletions nixos/modules/system/boot/binfmt.nix
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Original file line number Diff line number Diff line change
Expand Up @@ -262,7 +262,9 @@ in
interpreter = mkDefault interpreterReg;
fixBinary = mkDefault useStaticEmulator;
wrapInterpreterInShell = mkDefault (!config.preserveArgvZero && !config.fixBinary);
interpreterSandboxPath = mkDefault (dirOf (dirOf config.interpreter));
interpreterSandboxPath = mkDefault (
if config.fixBinary then null else dirOf (dirOf config.interpreter)
);
}
// (magics.${system} or (throw "Cannot create binfmt registration for system ${system}"))
);
Expand All @@ -276,10 +278,13 @@ in
let
ruleFor = system: cfg.registrations.${system};
hasWrappedRule = lib.any (system: (ruleFor system).wrapInterpreterInShell) cfg.emulatedSystems;
allFixBinary = lib.all (system: (ruleFor system).fixBinary) cfg.emulatedSystems;
in
[ "/run/binfmt" ]
lib.optional (!allFixBinary) "/run/binfmt"
++ lib.optional hasWrappedRule "${pkgs.bash}"
++ (map (system: (ruleFor system).interpreterSandboxPath) cfg.emulatedSystems);
++ lib.filter (x: x != null) (
map (system: (ruleFor system).interpreterSandboxPath) cfg.emulatedSystems
);
};

environment.etc."binfmt.d/nixos.conf".source = builtins.toFile "binfmt_nixos.conf" (
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14 changes: 13 additions & 1 deletion nixos/tests/systemd-binfmt.nix
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Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,12 @@ in
chroot = makeTest {
name = "systemd-binfmt-chroot";
nodes.machine =
{ pkgs, lib, ... }:
{
pkgs,
lib,
config,
...
}:
{
boot.binfmt.emulatedSystems = [
"aarch64-linux"
Expand All @@ -121,6 +126,13 @@ in
echo 42 | chroot /tmp/chroot /yaml2json | grep 42
'')
];

assertions = [
{
assertion = config.nix.settings.extra-sandbox-paths == [ ];
message = "Using binfmt_misc with static emulators, nix.settings.extra-sandbox-paths should be empty";
}
];
};
testScript = ''
machine.start()
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