Review follow-up to #751.
The offload path could not actually run: onBeforeBlobUpload goes through
HookBus.transform, which capped every handler at the 5s default. A handler
that pushes the file to an external store blows past that, and on timeout
the error is swallowed, the original file id is kept, and the composer
attaches the big file anyway - silently - while three such timeouts in a
minute auto-disable the plugin. Buses can now carry their own per-handler
budget and this one gets 120s. The same ceiling existed inside the sandbox,
where http.post/http.fetch were bounded by the 30s default API timeout;
those two are transfers rather than round-trips and now get 120s as well.
PRIVILEGED_ONLY_METHODS listed 'upfiles.set', which matches no dispatched
method - the dispatcher calls it 'upfiles.save'. So the write was never
tier-gated despite the comment saying it was, and an untrusted plugin with
email:blob-write could replace the bytes of a file the user was about to
send. Fixed the name. Relaxing the read while that stayed open was the
wrong order.
Moving upfiles.get to email:blob-read is kept, but it is a wider grant than
the PR described: onBeforeBlobUpload hands the file id to every registered
handler, so the id is not a secret and any untrusted plugin holding
email:blob-read can read every file the user attaches. The consent copy now
says that; email:blob-write's copy was describing the read and now describes
the replace it actually gates.
Also in the composer offload path:
- sanitize the handler's html before it reaches the document and the sent
message, and insert it through the editor at the caret rather than
concatenating it after the signature and quoted block
- honour an abort that lands while the handler is offloading
- delete the right staged file when the handler re-saved it under a new id
via upfiles.save, which otherwise stranded a copy in IndexedDB forever
Linus Rath
Ctaoist