diff options
Diffstat (limited to 'nixos/modules/services/backup/syncoid.nix')
| -rw-r--r-- | nixos/modules/services/backup/syncoid.nix | 435 |
1 files changed, 291 insertions, 144 deletions
diff --git a/nixos/modules/services/backup/syncoid.nix b/nixos/modules/services/backup/syncoid.nix index fff119c2cf0..73b01d4b53f 100644 --- a/nixos/modules/services/backup/syncoid.nix +++ b/nixos/modules/services/backup/syncoid.nix @@ -4,169 +4,316 @@ with lib; let cfg = config.services.syncoid; -in { - # Interface + # Extract local dasaset names (so no datasets containing "@") + localDatasetName = d: optionals (d != null) ( + let m = builtins.match "([^/@]+[^@]*)" d; in + optionals (m != null) m + ); - options.services.syncoid = { - enable = mkEnableOption "Syncoid ZFS synchronization service"; + # Escape as required by: https://www.freedesktop.org/software/systemd/man/systemd.unit.html + escapeUnitName = name: + lib.concatMapStrings (s: if lib.isList s then "-" else s) + (builtins.split "[^a-zA-Z0-9_.\\-]+" name); - interval = mkOption { - type = types.str; - default = "hourly"; - example = "*-*-* *:15:00"; - description = '' - Run syncoid at this interval. The default is to run hourly. + # Function to build "zfs allow" and "zfs unallow" commands for the + # filesystems we've delegated permissions to. + buildAllowCommand = zfsAction: permissions: dataset: lib.escapeShellArgs [ + # Here we explicitly use the booted system to guarantee the stable API needed by ZFS + "-+/run/booted-system/sw/bin/zfs" + zfsAction + cfg.user + (concatStringsSep "," permissions) + dataset + ]; +in +{ - The format is described in - <citerefentry><refentrytitle>systemd.time</refentrytitle> - <manvolnum>7</manvolnum></citerefentry>. - ''; - }; + # Interface - user = mkOption { - type = types.str; - default = "root"; - example = "backup"; - description = '' - The user for the service. Sudo or ZFS privilege delegation must be - configured to use a user other than root. - ''; - }; + options.services.syncoid = { + enable = mkEnableOption "Syncoid ZFS synchronization service"; - sshKey = mkOption { - type = types.nullOr types.path; - # Prevent key from being copied to store - apply = mapNullable toString; - default = null; - description = '' - SSH private key file to use to login to the remote system. Can be - overridden in individual commands. - ''; - }; + interval = mkOption { + type = types.str; + default = "hourly"; + example = "*-*-* *:15:00"; + description = '' + Run syncoid at this interval. The default is to run hourly. - commonArgs = mkOption { - type = types.listOf types.str; - default = []; - example = [ "--no-sync-snap" ]; - description = '' - Arguments to add to every syncoid command, unless disabled for that - command. See - <link xlink:href="https://github.com/jimsalterjrs/sanoid/#syncoid-command-line-options"/> - for available options. - ''; - }; + The format is described in + <citerefentry><refentrytitle>systemd.time</refentrytitle> + <manvolnum>7</manvolnum></citerefentry>. + ''; + }; - commands = mkOption { - type = types.attrsOf (types.submodule ({ name, ... }: { - options = { - source = mkOption { - type = types.str; - example = "pool/dataset"; - description = '' - Source ZFS dataset. Can be either local or remote. Defaults to - the attribute name. - ''; - }; + user = mkOption { + type = types.str; + default = "syncoid"; + example = "backup"; + description = '' + The user for the service. ZFS privilege delegation will be + automatically configured for any local pools used by syncoid if this + option is set to a user other than root. The user will be given the + "hold" and "send" privileges on any pool that has datasets being sent + and the "create", "mount", "receive", and "rollback" privileges on + any pool that has datasets being received. + ''; + }; - target = mkOption { - type = types.str; - example = "user@server:pool/dataset"; - description = '' - Target ZFS dataset. Can be either local - (<replaceable>pool/dataset</replaceable>) or remote - (<replaceable>user@server:pool/dataset</replaceable>). - ''; - }; + group = mkOption { + type = types.str; + default = "syncoid"; + example = "backup"; + description = "The group for the service."; + }; - recursive = mkOption { - type = types.bool; - default = false; - description = '' - Whether to also transfer child datasets. - ''; - }; + sshKey = mkOption { + type = types.nullOr types.path; + # Prevent key from being copied to store + apply = mapNullable toString; + default = null; + description = '' + SSH private key file to use to login to the remote system. Can be + overridden in individual commands. + ''; + }; - sshKey = mkOption { - type = types.nullOr types.path; - # Prevent key from being copied to store - apply = mapNullable toString; - description = '' - SSH private key file to use to login to the remote system. - Defaults to <option>services.syncoid.sshKey</option> option. - ''; - }; + commonArgs = mkOption { + type = types.listOf types.str; + default = [ ]; + example = [ "--no-sync-snap" ]; + description = '' + Arguments to add to every syncoid command, unless disabled for that + command. See + <link xlink:href="https://github.com/jimsalterjrs/sanoid/#syncoid-command-line-options"/> + for available options. + ''; + }; - sendOptions = mkOption { - type = types.separatedString " "; - default = ""; - example = "Lc e"; - description = '' - Advanced options to pass to zfs send. Options are specified - without their leading dashes and separated by spaces. - ''; - }; + service = mkOption { + type = types.attrs; + default = { }; + description = '' + Systemd configuration common to all syncoid services. + ''; + }; - recvOptions = mkOption { - type = types.separatedString " "; - default = ""; - example = "ux recordsize o compression=lz4"; - description = '' - Advanced options to pass to zfs recv. Options are specified - without their leading dashes and separated by spaces. - ''; - }; + commands = mkOption { + type = types.attrsOf (types.submodule ({ name, ... }: { + options = { + source = mkOption { + type = types.str; + example = "pool/dataset"; + description = '' + Source ZFS dataset. Can be either local or remote. Defaults to + the attribute name. + ''; + }; - useCommonArgs = mkOption { - type = types.bool; - default = true; - description = '' - Whether to add the configured common arguments to this command. - ''; - }; + target = mkOption { + type = types.str; + example = "user@server:pool/dataset"; + description = '' + Target ZFS dataset. Can be either local + (<replaceable>pool/dataset</replaceable>) or remote + (<replaceable>user@server:pool/dataset</replaceable>). + ''; + }; - extraArgs = mkOption { - type = types.listOf types.str; - default = []; - example = [ "--sshport 2222" ]; - description = "Extra syncoid arguments for this command."; - }; + recursive = mkEnableOption ''the transfer of child datasets''; + + sshKey = mkOption { + type = types.nullOr types.path; + # Prevent key from being copied to store + apply = mapNullable toString; + description = '' + SSH private key file to use to login to the remote system. + Defaults to <option>services.syncoid.sshKey</option> option. + ''; }; - config = { - source = mkDefault name; - sshKey = mkDefault cfg.sshKey; + + sendOptions = mkOption { + type = types.separatedString " "; + default = ""; + example = "Lc e"; + description = '' + Advanced options to pass to zfs send. Options are specified + without their leading dashes and separated by spaces. + ''; }; - })); - default = {}; - example = literalExample '' - { - "pool/test".target = "root@target:pool/test"; - } - ''; - description = "Syncoid commands to run."; - }; + + recvOptions = mkOption { + type = types.separatedString " "; + default = ""; + example = "ux recordsize o compression=lz4"; + description = '' + Advanced options to pass to zfs recv. Options are specified + without their leading dashes and separated by spaces. + ''; + }; + + useCommonArgs = mkOption { + type = types.bool; + default = true; + description = '' + Whether to add the configured common arguments to this command. + ''; + }; + + service = mkOption { + type = types.attrs; + default = { }; + description = '' + Systemd configuration specific to this syncoid service. + ''; + }; + + extraArgs = mkOption { + type = types.listOf types.str; + default = [ ]; + example = [ "--sshport 2222" ]; + description = "Extra syncoid arguments for this command."; + }; + }; + config = { + source = mkDefault name; + sshKey = mkDefault cfg.sshKey; + }; + })); + default = { }; + example = literalExample '' + { + "pool/test".target = "root@target:pool/test"; + } + ''; + description = "Syncoid commands to run."; }; + }; - # Implementation - - config = mkIf cfg.enable { - systemd.services.syncoid = { - description = "Syncoid ZFS synchronization service"; - script = concatMapStringsSep "\n" (c: lib.escapeShellArgs - ([ "${pkgs.sanoid}/bin/syncoid" ] - ++ (optionals c.useCommonArgs cfg.commonArgs) - ++ (optional c.recursive "-r") - ++ (optionals (c.sshKey != null) [ "--sshkey" c.sshKey ]) - ++ c.extraArgs - ++ [ "--sendoptions" c.sendOptions - "--recvoptions" c.recvOptions - c.source c.target - ])) (attrValues cfg.commands); - after = [ "zfs.target" ]; - serviceConfig.User = cfg.user; - startAt = cfg.interval; + # Implementation + + config = mkIf cfg.enable { + users = { + users = mkIf (cfg.user == "syncoid") { + syncoid = { + group = cfg.group; + isSystemUser = true; + # For syncoid to be able to create /var/lib/syncoid/.ssh/ + # and to use custom ssh_config or known_hosts. + home = "/var/lib/syncoid"; + createHome = false; + }; + }; + groups = mkIf (cfg.group == "syncoid") { + syncoid = { }; }; }; - meta.maintainers = with maintainers; [ lopsided98 ]; - } + systemd.services = mapAttrs' + (name: c: + nameValuePair "syncoid-${escapeUnitName name}" (mkMerge [ + { + description = "Syncoid ZFS synchronization from ${c.source} to ${c.target}"; + after = [ "zfs.target" ]; + startAt = cfg.interval; + # syncoid may need zpool to get feature@extensible_dataset + path = [ "/run/booted-system/sw/bin/" ]; + serviceConfig = { + ExecStartPre = + # Permissions snapshot and destroy are in case --no-sync-snap is not used + (map (buildAllowCommand "allow" [ "bookmark" "hold" "send" "snapshot" "destroy" ]) (localDatasetName c.source)) ++ + (map (buildAllowCommand "allow" [ "create" "mount" "receive" "rollback" ]) (localDatasetName c.target)); + ExecStopPost = + # Permissions snapshot and destroy are in case --no-sync-snap is not used + (map (buildAllowCommand "unallow" [ "bookmark" "hold" "send" "snapshot" "destroy" ]) (localDatasetName c.source)) ++ + (map (buildAllowCommand "unallow" [ "create" "mount" "receive" "rollback" ]) (localDatasetName c.target)); + ExecStart = lib.escapeShellArgs ([ "${pkgs.sanoid}/bin/syncoid" ] + ++ optionals c.useCommonArgs cfg.commonArgs + ++ optional c.recursive "-r" + ++ optionals (c.sshKey != null) [ "--sshkey" c.sshKey ] + ++ c.extraArgs + ++ [ + "--sendoptions" + c.sendOptions + "--recvoptions" + c.recvOptions + "--no-privilege-elevation" + c.source + c.target + ]); + User = cfg.user; + Group = cfg.group; + StateDirectory = [ "syncoid" ]; + StateDirectoryMode = "700"; + # Prevent SSH control sockets of different syncoid services from interfering + PrivateTmp = true; + # Permissive access to /proc because syncoid + # calls ps(1) to detect ongoing `zfs receive`. + ProcSubset = "all"; + ProtectProc = "default"; + + # The following options are only for optimizing: + # systemd-analyze security | grep syncoid-'*' + AmbientCapabilities = ""; + CapabilityBoundingSet = ""; + DeviceAllow = [ "/dev/zfs" ]; + LockPersonality = true; + MemoryDenyWriteExecute = true; + NoNewPrivileges = true; + PrivateDevices = true; + PrivateMounts = true; + PrivateNetwork = mkDefault false; + PrivateUsers = true; + ProtectClock = true; + ProtectControlGroups = true; + ProtectHome = true; + ProtectHostname = true; + ProtectKernelLogs = true; + ProtectKernelModules = true; + ProtectKernelTunables = true; + ProtectSystem = "strict"; + RemoveIPC = true; + RestrictAddressFamilies = [ "AF_UNIX" "AF_INET" "AF_INET6" ]; + RestrictNamespaces = true; + RestrictRealtime = true; + RestrictSUIDSGID = true; + RootDirectory = "/run/syncoid/${escapeUnitName name}"; + RootDirectoryStartOnly = true; + BindPaths = [ "/dev/zfs" ]; + BindReadOnlyPaths = [ builtins.storeDir "/etc" "/run" "/bin/sh" ]; + # Avoid useless mounting of RootDirectory= in the own RootDirectory= of ExecStart='s mount namespace. + InaccessiblePaths = [ "-+/run/syncoid/${escapeUnitName name}" ]; + MountAPIVFS = true; + # Create RootDirectory= in the host's mount namespace. + RuntimeDirectory = [ "syncoid/${escapeUnitName name}" ]; + RuntimeDirectoryMode = "700"; + SystemCallFilter = [ + "@system-service" + # Groups in @system-service which do not contain a syscall listed by: + # perf stat -x, 2>perf.log -e 'syscalls:sys_enter_*' syncoid … + # awk >perf.syscalls -F "," '$1 > 0 {sub("syscalls:sys_enter_","",$3); print $3}' perf.log + # systemd-analyze syscall-filter | grep -v -e '#' | sed -e ':loop; /^[^ ]/N; s/\n //; t loop' | grep $(printf ' -e \\<%s\\>' $(cat perf.syscalls)) | cut -f 1 -d ' ' + "~@aio" + "~@chown" + "~@keyring" + "~@memlock" + "~@privileged" + "~@resources" + "~@setuid" + "~@timer" + ]; + SystemCallArchitectures = "native"; + # This is for BindPaths= and BindReadOnlyPaths= + # to allow traversal of directories they create in RootDirectory=. + UMask = "0066"; + }; + } + cfg.service + c.service + ])) + cfg.commands; + }; + + meta.maintainers = with maintainers; [ julm lopsided98 ]; +} |