[tahoe-dev] Authority to DoS via WAPI

Toby Murray toby.murray at comlab.ox.ac.uk
Wed Jan 14 20:31:30 UTC 2009


Hi,

I'm pretty new to Tahoe. Let me first say how insanely awesome it is. 

I'd like to experiment with building distributed web applications,
backed by a tahoe grid, ala tiddly on tahoe. The idea would be to host a
web application at app.example.com . Run a tahoe "friendnet" grid to
serve as the backing store for the web application. Use some
load-balancing dynamic DNS to resolve app.example.com to any of the
nodes in the friendnet. This way the web app can be scaled as its number
of users increases simply by adding nodes to the grid. How cool.

Anyway, I have a concern with the current Web Application Programming
Interface (wapi), that anyone who knows the IP address of a node on a
tahoe grid can upload arbitrary content to that grid, thereby exhausting
disk space on its storage servers and consuming the entire grid. 

Would it be possible to alter the (default) web interface so that the
authority to upload files and create directories is refified itself by
an unguessable URI that is perhaps derived from the introducer FURL so
that it is the same for all nodes in the grid? (The upload/create-dir
URIs of course would need to be constant for any node in the grid.)

It seems strange to require an unguessable (F)URL to join the grid but
not one to consume space on it.

Cheers heaps

Toby 




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