The rclone core does not sanitise ".." in an object's Remote(). Such a name can
arrive from a malicious or buggy backend - an object store permits keys
containing ".." or a leading "/" - and, if acted on, lets a listing or transfer
escape the configured root. A source object named "../../other/x" is copied to
"other/x" outside the destination root, and a crafted listing name surfaces
outside the directory being listed.
Add list.RemoteEscapesRoot, which reports whether a Remote climbs above the
root when joined onto it, and list.RemoveEscaping, which drops and logs such
entries.
Apply RemoveEscaping unconditionally - independent of the include/exclude
filters - at the three per-entry filtering points every listing passes through:
filterDir, walk.listR and walk.walkRDirTree (recursive ListR).
operations.StatJSON calls List and NewObject directly, bypassing those, so it
rejects an escaping remote up front.
This confines every backend at once, so no per-backend change is needed.
This involved adding the Fs() method to DirEntry as it is needed in
the metadata mapper.
Unspecialised fs.Dir objects will return a new fs.Unknown from their
Fs() methods as they are not specific to any given Fs.
- Change rclone/fs interfaces to accept context.Context
- Update interface implementations to use context.Context
- Change top level usage to propagate context to lover level functions
Context propagation is needed for stopping transfers and passing other
request-scoped values.
The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.
The new code layout is documented in CONTRIBUTING.
Nick Craig-Wood
Aleksandar JankovicandNick Craig-Wood