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On Wed, Jun 14, 2017 at 06:20:10PM -0700, Andrew Morgan wrote:
> On 06/14/2017 03:11 PM, Marek Marczykowski-Górecki wrote:
> > On Wed, Jun 14, 2017 at 03:03:00AM -0700, Andrew Morgan wrote:
> >> # Denying Local Read Permissions on Untrusted Files
> > 
> >> To prevent this mark otherwise being accidentally destroyed on the
> >> originating VM, we can simply deny all users permission to read or write
> >> from it (through a chmod 0). Props to my mentor Marek for the suggestion.
> > 
> >> This has the one hiccup of which we can no longer read a file's Extended
> >> File Attributes, however our code can simply 'unlock' the file before
> >> processing it by chmod'ing the file back to 0644 before processing, and
> >> 'locking' it again afterwards.
> > 
> > Also worth checking how other file manager actions handle this - moving
> > file, viewing its properties, copying it...
> > And even if copying do work, check if xattrs are preserved.
> 
> Well as we `chmod 0` the file copying won't work as the file cannot be
> read. This may present some UX issues, and we should inform the user
> that a file must be 'unlocked' first before it can be moved.
> 
> From my testing xattrs are preserved in Nautilus when
> copying/moving/renaming, while Dolphin preserves it with renaming and
> moving, but not copying.
> 
> We /could/ provide functionality in our extensions to move/copy/rename
> the file such that it would be able to unlock and relock the file. I
> could add this to the list of stretch goals perhaps.

Lets keep it very low on the priority list.

> >> # Conclusion
> > 
> >> Now that the GUI is all finished, it's time to work on making the File
> >> Managers (Nautilus and Dolphin) aware of untrusted files. While it's
> >> easy enough to check for untrusted files on a right-click basis, we also
> >> need to check their status on a single or double left-click (i.e when a
> >> file is opened).
> > 
> >> Originally I planned to patch the File Managers to allow for running
> >> code on a left-click, however after creating the Nautilus extension, it
> >> seems to already do this by default. Coupled with the fact that files
> >> are no longer locally editable and thus cannot be opened automatically,
> >> we may not actually need to patch Nautilus at all!
> > 
> > \o/
> 
> So turns out while we do get a ping in our extension when a user tries
> to open a file, we still need to prevent the file from attempting to be
> opened - otherwise a rather annoying message will pop up complaining it
> can't be read.
> 
> Additionally, I'm not entirely sure if the ping we receive is
> indistinguishable from the one we get when a user right-clicks a file.
> 
> So patching will still be necessary to:
> 
> 1. Prevent opening of the file all-together.

Not really preventing - just changing the action (application to open
the file).

> 2. Send a separate message to the extension that a user is opening a
> file, versus just clicking on it. (there may be a workaround for this
> one, still looking)
> 
> > 
> >> Dolphin may still require a patch, but I'll be looking for ways to
> >> possibly get away with not needing to while working on the Nautilus
> >> version first.
> > 
> >> Any and all feedback is appreciated, see you all in a week!
> > 
> > 
> > 
> 
> 




- -- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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