ubuntu-phone team mailing list archive

[Jamie Strandboge <jamie@xxxxxxxxxxxxx>]

On 11/13/2014 08:25 AM, Marc Deslauriers wrote:
> On 2014-11-12 11:58 AM, Jamie Strandboge wrote:
>> Pulling into CC various stakeholders.
>>
>> On 11/12/2014 09:47 AM, Florian Boucault wrote:

...

>>> The camera and the gallery app today are authorized to read/write in
>>> /home/$USER/Pictures and /home/$USER/Videos.
>>> Soon they will also need to be able to read/write in the similar directories of
>>> the SD card, for example:
>>> - /media/phablet/064a-7494/Pictures
>>> - /media/phablet/064a-7494/Videos

...

>> We can then do something similar for apps. Eg, the predictable hierarchy for
>> apps might be:
>>   /media/$USER/$SDCARD_ID/.cache/$APP_PKGNAME
>>   /media/$USER/$SDCARD_ID/.config/$APP_PKGNAME
>>   /media/$USER/$SDCARD_ID/.local/share/$APP_PKGNAME
>>
>> such that the AppArmor templates add:
>>   owner /media/*/*/.cache/@{APP_PKGNAME}/         rw,
>>   owner /media/*/*/.cache/@{APP_PKGNAME}/**       mrwkl,
>>   owner /media/*/*/.config/@{APP_PKGNAME}/        rw,
>>   owner /media/*/*/.config/@{APP_PKGNAME}/**      mrwkl,
>>   owner /media/*/*/.local/share/@{APP_PKGNAME}/   rw,
>>   owner /media/*/*/.local/share/@{APP_PKGNAME}/** mrwklix,
> 
> This is problematic. As you mention later on, sdcards mostly use vfat, which
> means file names are case insensitive. This opens up a lot of issues when trying
> to confine apps to specific directories, and also creates issues with data loss
> if the system isn't designed to cope well.
> 
> If we want app-specific directories on the sdcard, we will likely have to
> require the card be formatted with a better filesystem, or we should punt on
> this for now.
> 

Ah yes, I forgot about the case-insensitive names. I also agree this is
problematic. With the global directories, we should therefore do:

# SD card: /media/<user>/<label>/...
owner /media/*/*/[Pp][Ii][Cc][Tt][Uu][Rr][Ee][Ss]/   r,
owner /media/*/*/[Pp][Ii][Cc][Tt][Uu][Rr][Ee][Ss]/** rwk,

That is easy enough.


Apps are hard though-- click-apparmor could be adjusted to instead of:
@{APP_APPNAME}="bar"
@{APP_PKGNAME}="com.ubuntu.developer.user.foo"

do:
@{APP_APPNAME}="[Bb][Aa][Rr]"
@{APP_PKGNAME}="[Cc][Oo][Mm].[Uu][Bb][Uu][Nn][Tt][Uu].[Dd][Ee][Vv][Ee][Ll][Oo][Pp][Ee][Rr].[Uu][Ss][Ee][Rr].[Ff][Oo][Oo]"

but yikes, I don't like that; plus I agree with your other points about what
happens when the card is pulled out. App-specific directories needs more thought
and planning.


-- 
Jamie Strandboge                 http://www.ubuntu.com/

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