linux-kernel - Re: proposal to refine capability checks when _rlimit

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Date: Wed, 3 Jan 2024 07:11:18 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: 孟敬姿 <mengjingzi@....ac.cn>
Cc: brauner@...nel.org, linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: proposal to refine capability checks when _rlimit_overlimit() is
 true

On Wed, Jan 03, 2024 at 11:12:28AM +0800, 孟敬姿 wrote:
> Hi!
> 
> We observed a potential refinement in the kernel/fork.c line 2368.
> Currently, both CAP_SYS_ADMIN and CAP_SYS_RESOURCE are checked when
> the limit is over system limit. We suggest considering an adjustment
> to utilize CAP_SYS_RESOURCE exclusively. Here's our rationale for this
> suggestion:

As I said when you proposed changing CAP permissions on the tty ioctls,
have you tried this and seen what actually breaks by doing so?  Please
audit the userspace code out there to ensure that what you are
attempting to propose actually would work, and then, if so, submit a
patch to do so.  Attempts of "wouldn't it be nice", don't go very far as
it shows that the work to do so hasn't actually been done.

thanks,

greg k-h