Val Markovic c4ff02def7 fix(systemd): support overrides for syncOwnership (#10602) ...

Syncthing docs in https://docs.syncthing.net/users/autostart.html#permissions
tell the user to set `AmbientCapabilities=CAP_CHOWN CAP_FOWNER` if the
user wishes to use the `syncOwnership` option.

https://github.com/syncthing/syncthing/pull/10421 broke `syncOwnership`
for users that followed that advice because the PR introduced
`CapabilityBoundingSet=` which cancels out any additional capabilities
granted with `AmbientCapabilities`.

(`AmbientCapabilities` _adds_ capabilities; `CapabilityBoundingSet`
_limits_ maximum capabilities to the specified set. Setting
`CapabilityBoundingSet` to an empty list prevents any capabilities from
being acquired in any way.)

This PR fixes the breakage by explicitly setting

    CapabilityBoundingSet=CAP_CHOWN CAP_FOWNER

This does _not_ grant any additional access rights to syncthing if the
user is not explicitly setting `AmbientCapabilities` as well, but it
does loosen the sandbox _a bit_. An attacker compromising the syncthing
process could now more easily expand their access to include
CAP_CHOWN/CAP_FOWNER even if the user is not setting
`AmbientCapabilities`.

Signed-off-by: Val Markovic <val@markovic.io>

2026-03-11 14:11:50 +01:00

9.4 KiB

Raw Blame History

View Raw