Re: Atomic non-durable file write API

[Greg Freemyer <greg.freemyer@gmail.com>]

On Tue, Dec 28, 2010 at 5:06 PM, Olaf van der Spek <olafvdspek@gmail.com> wrote:
> On Tue, Dec 28, 2010 at 11:00 PM, Greg Freemyer <greg.freemyer@gmail.com> wrote:
>> create temp file
>> write out new data
>> delete old file
>> rename temp file to primary name
>> ===
>>
>> If so there is still a little window of vulnerability where the whole
>> file can be lost.  (Or at least only the temp file is present).
>
> Delete isn't used, rename will overwrite the old file. So it's safe.
> Meta-data is probably lost, file owner is certainly lost.
>
> Olaf

So ACLs are lost?

That seems like a potentially bigger issue than loosing the owner/group info.

And I assume if the owner changes, then the new owner has privileges
to modify ACLs he didn't have previously.

So if I want to instigate a simple denial of service in a multi-user
environment, I edit a few key docs that I have privileges to edit.  By
doing so I take ownership.  As owner I  change the permissions and
ACLs so that no one but me can access them.

Seems like a security hole to me.

Greg
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