[Python-Dev] Remove tempfile.mktemp()

[Ivan Pozdeev]

Before we can say if something is "secure" or not, we need a threat model -- i.e we need to agree which use cases we are protecting and from 
what threats.

So far, I've seen these use cases:

1. File for the current process' private use
2. File/file name generated by the current process; written by another process, read by current one
3. File name generated by the current process; written by the current process, read by another one

And the following threats, three axes:

a. Processes run as other users
b. Processes run as the same user (or a user that otherwise automatically has access to all your files)

1. Accidental collision from a process that uses CREATE_NEW or equivalent
2. Accidental collision from a process that doesn't use CREATE_NEW or equivalent
3. Malicious code creating files at random
4. Malicious code actively monitoring file creation

-1. read
-2. write

E.g. for threat b-4), it's not safe to use named files for IPC at all, only case 1 can be secured (with exclusive open).

On 19.03.2019 16:03, Stéphane Wirtel wrote:

> Hi,
>
> Context: raise a warning or remove tempfile.mktemp()
> BPO: https://bugs.python.org/issue36309
>
> Since 2.3, this function is deprecated in the documentation, just in the
> documentation. In the code, there is a commented RuntimeWarning.
> Commented by Guido in 2002, because the warning was too annoying (and I
> understand ;-)).
>
> So, in this BPO, we start to discuss about the future of this function
> and Serhiy proposed to discuss on the Python-dev mailing list.
>
> Question: Should we drop it or add a (Pending)DeprecationWarning?
>
> Suggestion and timeline:
>
> 3.8, we raise a PendingDeprecationWarning
>      * update the code
>      * update the documentation
>      * update the tests
>        (check a PendingDeprecationWarning if sys.version_info == 3.8)
>
> 3.9, we change PendingDeprecationWarning to DeprecationWarning
>        (check DeprecationWarning if sys.version_info == 3.9)
>
> 3.9+, we drop tempfile.mktemp()
>
> What do you suggest?
>
> Have a nice day and thank you for your feedback.
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-- 
Regards,
Ivan