Re: [RFD] Common userspace tool for fscypto

From: Richard Weinberger
Date: Tue Nov 29 2016 - 17:00:21 EST


On 29.11.2016 22:42, Joe Richey wrote:
> Hi Richard,
> I'm Joe Richey, and I work on Mike's team. We've been playing around
> with a few design
> ideas regarding a tool for managing filesystem encryption. After going
> though some iterations
> with Ted, we have a fairly good idea about where to head design wise,
> and I'm working on a
> design document for it. It's a bit preliminary at this point, but I
> can share it if you want.
> Our goal is to have a finished doc by end of Q4 and then get your and
> Jaegeuk's feedback.

Thanks for your quick response!
I hoped you had already some code, but having a decent design document
is also nice. I'm eager to read it.

Do you also plan to address d/page cache related issues?
i.e. when two users are logged into the system user rw
is able to see decrypted file names and contents in /home/dags/
if user dags installs a key and accessed a file.

Or files in /home/dags/ are still readable even after
user dags purged the key.

The tool could play games with CLONE_NEWNS to hide directories.
To provide a correct "logout" we could expose shrink_dcache_parent()
to usespace such that the emerging tool can purge the key and flush
the dcache on the encrypted directory. But I fear exposing shrink_dcache_parent()
is not a good idea. :-)

Just some random ideas...