[Sugar-devel] Advice request: XO sound recording

Walter Bender walter.bender at gmail.com
Mon Oct 4 10:44:36 EDT 2010

On Mon, Oct 4, 2010 at 10:15 AM, James Simmons <nicestep at gmail.com> wrote:
> Sascha,
> I fully support the way Activities are not allowed write access to
> anything but the datastore and their own directories.  I even support
> not being able to list out Journal entries at the same time you do
> network access.  If we get to the point where an Activity cannot list
> out Journal entries (other than using the Object Chooser) at any time
> then I've got a beef.
> I have tried the Object Chooser.  In Sugar .82 it had some serious
> bugs, could not list out only those entries you wanted to look at, and
> was slow and ugly.  A big part of my book is explaining how to write
> Activities that will run on .82 as well as later versions of Sugar,
> and there was no way to make the Object Chooser a part of that
> strategy.  As a result I did not discuss it in the book, but did
> describe how to write your own object choosing code.  What I described
> works well and answers a legitimate need.  In my opinion, nothing I am
> recommending would allow anyone to make a malicious Activity (assuming
> that listing entries in the data store was blocked during network
> access).

Whereas all of the major Sugar deployments (.uy, .pe, .py. etc.) are
transitioning to 0.84 or 0.88, there is less of a concern in my mind
to make activities run "on .82 as well as later versions." That said,
I would want activities to run on 0.82, but perhaps in a lesser form
than on more recent Sugar releases.


> James Simmons
>> Date: Mon, 04 Oct 2010 10:11:00 +0200
>> From: Sascha Silbe <sascha-ml-reply-to-2010-3 at silbe.org>
>> Subject: Re: [Sugar-devel] Advice request: XO sound recording
>> To: sugar-devel <sugar-devel at lists.sugarlabs.org>
>> Message-ID: <1286177910-sup-2358 at twin.sascha.silbe.org>
>> Content-Type: text/plain; charset="utf-8"
>> Excerpts from James Simmons's message of Mon Oct 04 01:28:03 +0200 2010:
>>> There is a chapter called "Fun With The Journal" which has examples of
>>> listing out Journal entries.  What you need to do is figure out what
>>> the MIME type of the Ogg entries in the Journal are and write code to
>>> list them.  Then you can put the entries in a GTK table and select
>>> them from there.
>> Just a word of caution: While access to the data store is unrestricted
>> because nobody got around to implement the access controls, this won't
>> be the case forever. In general you should only assume that you have
>> access to the entry belonging to the currently running activity session
>> (P_DOCUMENT [1,2]). The Object Chooser is a powerbox [3] that will grant
>> your activity access to an additional entry selected by the user (and
>> only that one entry, nothing else).
>> While activities can request additional permissions [4] only certain
>> combinations will be granted automatically. In particular listing data
>> store entries is mutually exclusive with network access [5]:
>>>> We solve this by allowing programs to request read-only permissions for
>>>> one type of document (e.g. image, audio, text, e-mail) at installation
>>>> time, but making that permission (#P_DOCUMENT_RO) mutually exclusive
>>>> with asking for any network access at all. A photo viewing program, in
>>>> other words, normally has no business connecting to the Internet.
>> While the user can explicitly grant activities additional permissions,
>> we should be careful not to train them to do this for a significant
>> number of activities as it would make the system pointless and vulnerable
>> to the attacks we're trying to guard the users against (e.g. [6]).
>> Sascha
>> [1] http://wiki.laptop.org/go/OLPC_Bitfrost#P_DOCUMENT:_file_store_service
>> [2] http://dev.laptop.org/git/security/tree/bitfrost.txt#n874
>> [3] http://en.wikipedia.org/wiki/File_dialog#Powerbox
>> [4] http://wiki.sugarlabs.org/go/Development_Team/Low-level_Activity_API#Permissions_Declarations
>> [5] http://wiki.laptop.org/go/OLPC_Bitfrost#P_DOCUMENT_RO
>> [6] http://wiki.laptop.org/go/OLPC_Bitfrost#Compromising_privacy_2
>> --
>> http://sascha.silbe.org/
>> http://www.infra-silbe.de/
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Walter Bender
Sugar Labs

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