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Date: Fri, 6 Sep 2019 18:06:25 +0200
From: Mickaël Salaün <mickael.salaun@....gouv.fr>
To: Florian Weimer <fweimer@...hat.com>, Mickaël Salaün
<mic@...ikod.net>
CC: <linux-kernel@...r.kernel.org>, Aleksa Sarai <cyphar@...har.com>, Alexei
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Subject: Re: [PATCH v2 1/5] fs: Add support for an O_MAYEXEC flag on
sys_open()
On 06/09/2019 17:56, Florian Weimer wrote:
> Let's assume I want to add support for this to the glibc dynamic loader,
> while still being able to run on older kernels.
>
> Is it safe to try the open call first, with O_MAYEXEC, and if that fails
> with EINVAL, try again without O_MAYEXEC?
The kernel ignore unknown open(2) flags, so yes, it is safe even for
older kernel to use O_MAYEXEC.
>
> Or do I risk disabling this security feature if I do that?
It is only a security feature if the kernel support it, otherwise it is
a no-op.
>
> Do we need a different way for recognizing kernel support. (Note that
> we cannot probe paths in /proc for various reasons.)
There is no need to probe for kernel support.
>
> Thanks,
> Florian
>
--
Mickaël Salaün
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