diff options
Diffstat (limited to 'nixos/modules/security/systemd-confinement.nix')
| -rw-r--r-- | nixos/modules/security/systemd-confinement.nix | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/nixos/modules/security/systemd-confinement.nix b/nixos/modules/security/systemd-confinement.nix index 0304749b8d109..041c900338864 100644 --- a/nixos/modules/security/systemd-confinement.nix +++ b/nixos/modules/security/systemd-confinement.nix @@ -79,13 +79,20 @@ in { description = '' The value `full-apivfs` (the default) sets up private {file}`/dev`, {file}`/proc`, - {file}`/sys` and {file}`/tmp` file systems in a separate user - name space. + {file}`/sys`, {file}`/tmp` and {file}`/var/tmp` file systems + in a separate user name space. If this is set to `chroot-only`, only the file system name space is set up along with the call to {manpage}`chroot(2)`. + In all cases, unless `serviceConfig.PrivateTmp=true` is set, + both {file}`/tmp` and {file}`/var/tmp` paths are added to `InaccessiblePaths=`. + This is to overcome options like `DynamicUser=true` + implying `PrivateTmp=true` without letting it being turned off. + Beware however that giving processes the `CAP_SYS_ADMIN` and `@mount` privileges + can let them undo the effects of `InaccessiblePaths=`. + ::: {.note} This doesn't cover network namespaces and is solely for file system level isolation. @@ -98,8 +105,12 @@ in { wantsAPIVFS = lib.mkDefault (config.confinement.mode == "full-apivfs"); in lib.mkIf config.confinement.enable { serviceConfig = { - RootDirectory = "/var/empty"; - TemporaryFileSystem = "/"; + ReadOnlyPaths = [ "+/" ]; + RuntimeDirectory = [ "confinement/${mkPathSafeName name}" ]; + RootDirectory = "/run/confinement/${mkPathSafeName name}"; + InaccessiblePaths = [ + "-+/run/confinement/${mkPathSafeName name}" + ]; PrivateMounts = lib.mkDefault true; # https://github.com/NixOS/nixpkgs/issues/14645 is a future attempt @@ -148,16 +159,6 @@ in { + " Please either define a separate service or find a way to run" + " commands other than ExecStart within the chroot."; } - { assertion = !cfg.serviceConfig.DynamicUser or false; - message = "${whatOpt "DynamicUser"}. Please create a dedicated user via" - + " the 'users.users' option instead as this combination is" - + " currently not supported."; - } - { assertion = cfg.serviceConfig ? ProtectSystem -> cfg.serviceConfig.ProtectSystem == false; - message = "${whatOpt "ProtectSystem"}. ProtectSystem is not compatible" - + " with service confinement as it fails to remount /usr within" - + " our chroot. Please disable the option."; - } ]) config.systemd.services); config.systemd.packages = lib.concatLists (lib.mapAttrsToList (name: cfg: let @@ -183,6 +184,13 @@ in { echo "BindReadOnlyPaths=$realprog:/bin/sh" >> "$serviceFile" ''} + # If DynamicUser= is enabled, PrivateTmp=true is implied (and cannot be turned off). + # so disable them unless PrivateTmp=true is explicitely set. + ${lib.optionalString (!cfg.serviceConfig.PrivateTmp) '' + echo "InaccessiblePaths=-+/tmp" >> "$serviceFile" + echo "InaccessiblePaths=-+/var/tmp" >> "$serviceFile" + ''} + while read storePath; do if [ -L "$storePath" ]; then # Currently, systemd can't cope with symlinks in Bind(ReadOnly)Paths, |