Re: Unmerged patches adding audit when protected_regular/fifos sysctl causes EACCES

From: Kees Cook
Date: Wed Sep 25 2019 - 16:12:42 EST


On Wed, Sep 25, 2019 at 02:58:28PM -0400, Jérémie Galarneau wrote:
> Hi Kees,
>
> I have noticed that the two top-most patches of your protected-creat
> branch were never merged upstream [1]. Those patches add audit logs
> whenever the protected_regular or protected_fifo sysctl prevent the
> creation of a file/fifo.
>
> They were mentioned in the v4 thread [2] of the "main" patch and
> seemed acceptable, but they were no longer mentioned in v5 [3], which
> was merged.
>
> Now that systemd enables those sysctls by default (v241+), I got
> bitten pretty hard by this check and it took me a while to figure out
> what was happening [4]. I ended up catching it by adding a bunch of
> printk(), including where you proposed to add an audit log statement.
>
> I just found your two patches while implementing what you proposed almost 1:1.
>
> Was there a reason why those were abandoned? Otherwise, would you mind
> resubmitting them?

Hi!

There was concern about getting buy-in from the audit folks delaying
things even more. Instead of waiting for that, as it had already taken
a long time to get consensus even on the functionality, they were
dropped.

I'll rebase them and send them out again; thanks for the ping!

-Kees

>
> Thanks!
> Jérémie
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/log/?h=kspp/userspace/protected-creat
> [2] https://lkml.org/lkml/2018/4/10/840
> [3] https://lore.kernel.org/lkml/20180416175918.GA13494@beast/
> [4] https://github.com/lttng/lttng-tools/commit/cf86ff2c4ababd01fea7ab2c9c289cb7c0a1bcd5
>
> --
> Jérémie Galarneau
> EfficiOS Inc.
> http://www.efficios.com

--
Kees Cook