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Date: Fri, 26 Apr 2024 04:25:40 +0100
From: Matthew Wilcox <willy@infradead.org>
To: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Kees Cook <keescook@chromium.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Suren Baghdasaryan <surenb@google.com>, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] alloc_tag: Tighten file permissions on /proc/allocinfo
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On Thu, Apr 25, 2024 at 08:58:34PM -0400, Kent Overstreet wrote:
> On Thu, Apr 25, 2024 at 05:43:33PM -0700, Kees Cook wrote:
> > All this said, I'm still not excited about any of these files living
> > in /proc at all -- we were supposed to use /sys for this kind of thing,
> > but its interface wasn't great for this kind of more "free-form" data,
> > and debugfs isn't good for production interfaces. /proc really should
> > only have pid information -- we end up exposing these top-level files to
> > every mount namespace with a /proc mount. :( But that's a yet-to-be-solved
> > problem...
> 
> It really wouldn't be that hard to relax the 4k file limit in sysfs.

It's a lot harder to relax the GregKH opposition to multiple values per
file in sysfs.