This allows apps that use /tmp as an IPC rendezvous point, such as those
that embed Chromium-derived browsers, to communicate between instances;
this would not previously have worked without --filesystem=/tmp, which
is a significant weakening of the sandbox.
It also allows /tmp to be shared with subsandboxes (if they are not
sandboxed more strictly).
The temporary directory is actually created in XDG_RUNTIME_DIR,
to avoid it becoming visible to unrelated apps that happen to have
--filesystem=/tmp.
Signed-off-by: Simon McVittie <smcv@collabora.com>
Simon McVittie
b65b3f6ead