When the upperdir of an overlayfs does not exist at mount time, systemd since v256 automatically creates it with default permissions and ownership (0755, root:root).
This ownership is often sufficient, so the overhead of using a helper unit to create the upper layer and apply the permissions of the lower layer before starting the overlayfs mount unit is not always necessary. Introduce the variable OVERLAYFS_INHERIT_LOWER_PERMISSIONS that can be used to control the creation of the helper unit. If set to "1", it will get created. Otherwise, systemd will create the directories and apply its defaults. Signed-off-by: Andreas Mützel <[email protected]> --- meta/classes-recipe/overlayfs.bbclass | 42 +++++++++++++++---- .../files/overlayfs-unit-create-dirs.mount.in | 13 ++++++ meta/files/overlayfs-unit.mount.in | 3 +- meta/lib/oe/overlayfs.py | 3 +- 4 files changed, 49 insertions(+), 12 deletions(-) create mode 100644 meta/files/overlayfs-unit-create-dirs.mount.in diff --git a/meta/classes-recipe/overlayfs.bbclass b/meta/classes-recipe/overlayfs.bbclass index a82763ec10..8a87624be3 100644 --- a/meta/classes-recipe/overlayfs.bbclass +++ b/meta/classes-recipe/overlayfs.bbclass @@ -48,6 +48,21 @@ # started after the ${PN}-overlays.service to make sure that all overlays are # mounted beforehand. # +# If the storage directories (upperdir and workdir) of the overlayfs do not +# exist when systemd mounts the overlayfs, systemd will create them with +# default permissions (mode 0755, owned by root:root). +# These permissions may be different from the actual permissions of the lower layer; +# in some cases, it is desirable to create the upper layer with the same owner and mode +# of the lower layer. +# To make the directory permissions of the upper directory match those of the lower +# directory, set OVERLAYFS_INHERIT_LOWER_PERMISSIONS to 1 for the respective overlay: +# +# OVERLAYFS_WRITABLE_PATHS[data] = "/usr/share/my-custom-application" +# OVERLAYFS_INHERIT_LOWER_PERMISSIONS[data] = 1 +# +# This will result in an additional helper unit that creates the upper and work +# directories and applies the correct permissions before the overlayfs is mounted. +# # Note: the class does not support /etc directory itself, because systemd depends on it # For /etc directory use overlayfs-etc class @@ -57,6 +72,7 @@ inherit systemd features_check OVERLAYFS_CREATE_DIRS_TEMPLATE ??= "${COREBASE}/meta/files/overlayfs-create-dirs.service.in" OVERLAYFS_MOUNT_UNIT_TEMPLATE ??= "${COREBASE}/meta/files/overlayfs-unit.mount.in" +OVERLAYFS_MOUNT_UNIT_TEMPLATE_WITH_CREATE_DIRS ??= "${COREBASE}/meta/files/overlayfs-unit-create-dirs.mount.in" OVERLAYFS_ALL_OVERLAYS_TEMPLATE ??= "${COREBASE}/meta/files/overlayfs-all-overlays.service.in" python do_create_overlayfs_units() { @@ -66,10 +82,12 @@ python do_create_overlayfs_units() { CreateDirsUnitTemplate = f.read() with open(d.getVar("OVERLAYFS_MOUNT_UNIT_TEMPLATE"), "r") as f: MountUnitTemplate = f.read() + with open(d.getVar("OVERLAYFS_MOUNT_UNIT_TEMPLATE_WITH_CREATE_DIRS"), "r") as f: + MountUnitWithHelperTemplate = f.read() with open(d.getVar("OVERLAYFS_ALL_OVERLAYS_TEMPLATE"), "r") as f: AllOverlaysTemplate = f.read() - def prepareUnits(data, lower): + def prepareUnits(data, lower, use_helper): from oe.overlayfs import helperUnitName args = { @@ -79,13 +97,18 @@ python do_create_overlayfs_units() { 'LOWERDIR': lower, } - bb.debug(1, "Generate systemd unit %s" % mountUnitName(lower)) - with open(os.path.join(d.getVar('WORKDIR'), mountUnitName(lower)), 'w') as f: - f.write(MountUnitTemplate.format(**args)) + if use_helper: + bb.debug(1, "Generate systemd unit %s" % mountUnitName(lower)) + with open(os.path.join(d.getVar('WORKDIR'), mountUnitName(lower)), 'w') as f: + f.write(MountUnitWithHelperTemplate.format(**args)) - bb.debug(1, "Generate helper systemd unit %s" % helperUnitName(lower)) - with open(os.path.join(d.getVar('WORKDIR'), helperUnitName(lower)), 'w') as f: - f.write(CreateDirsUnitTemplate.format(**args)) + bb.debug(1, "Generate helper systemd unit %s" % helperUnitName(lower)) + with open(os.path.join(d.getVar('WORKDIR'), helperUnitName(lower)), 'w') as f: + f.write(CreateDirsUnitTemplate.format(**args)) + else: + bb.debug(1, "Generate basic systemd unit %s" % mountUnitName(lower)) + with open(os.path.join(d.getVar('WORKDIR'), mountUnitName(lower)), 'w') as f: + f.write(MountUnitTemplate.format(**args)) def prepareGlobalUnit(dependentUnits): from oe.overlayfs import allOverlaysUnitName @@ -109,7 +132,8 @@ python do_create_overlayfs_units() { for lower in lowerList.split(): bb.debug(1, "Prepare mount unit for %s with data mount point %s" % (lower, d.getVarFlag('OVERLAYFS_MOUNT_POINT', mountPoint))) - prepareUnits(d.getVarFlag('OVERLAYFS_MOUNT_POINT', mountPoint), lower) + use_helper = d.getVarFlag('OVERLAYFS_INHERIT_LOWER_PERMISSIONS', mountPoint) == '1' + prepareUnits(d.getVarFlag('OVERLAYFS_MOUNT_POINT', mountPoint), lower, use_helper) mountUnitList.append(mountUnitName(lower)) # set up one unit, which depends on all mount units, so users can set @@ -138,5 +162,5 @@ do_install:append() { done } -do_create_overlayfs_units[vardeps] += "OVERLAYFS_WRITABLE_PATHS" +do_create_overlayfs_units[vardeps] += "OVERLAYFS_WRITABLE_PATHS OVERLAYFS_INHERIT_LOWER_PERMISSIONS" addtask create_overlayfs_units before do_install diff --git a/meta/files/overlayfs-unit-create-dirs.mount.in b/meta/files/overlayfs-unit-create-dirs.mount.in new file mode 100644 index 0000000000..9c117f2c52 --- /dev/null +++ b/meta/files/overlayfs-unit-create-dirs.mount.in @@ -0,0 +1,13 @@ +[Unit] +Description=Overlayfs mount unit {LOWERDIR} +Requires={CREATE_DIRS_SERVICE} +After={CREATE_DIRS_SERVICE} + +[Mount] +What=overlay +Where={LOWERDIR} +Type=overlay +Options=lowerdir={LOWERDIR},upperdir={DATA_MOUNT_POINT}/upper{LOWERDIR},workdir={DATA_MOUNT_POINT}/workdir{LOWERDIR} + +[Install] +WantedBy=multi-user.target diff --git a/meta/files/overlayfs-unit.mount.in b/meta/files/overlayfs-unit.mount.in index 9c117f2c52..eb78d2cb4f 100644 --- a/meta/files/overlayfs-unit.mount.in +++ b/meta/files/overlayfs-unit.mount.in @@ -1,7 +1,6 @@ [Unit] Description=Overlayfs mount unit {LOWERDIR} -Requires={CREATE_DIRS_SERVICE} -After={CREATE_DIRS_SERVICE} +RequiresMountsFor={DATA_MOUNT_POINT} [Mount] What=overlay diff --git a/meta/lib/oe/overlayfs.py b/meta/lib/oe/overlayfs.py index 8b88900f71..c26fae07bd 100644 --- a/meta/lib/oe/overlayfs.py +++ b/meta/lib/oe/overlayfs.py @@ -46,7 +46,8 @@ def unitFileList(d): continue for path in mountPointList.split(): fileList.append(mountUnitName(path)) - fileList.append(helperUnitName(path)) + if d.getVarFlag('OVERLAYFS_INHERIT_LOWER_PERMISSIONS', mountPoint) == '1': + fileList.append(helperUnitName(path)) fileList.append(allOverlaysUnitName(d)) -- 2.54.0
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