linux-kernel - Re: [PATCH v2] proc: allow restricting /proc/pid/mem writes

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Message-ID: <202403040951.C63C3DF5@keescook>
Date: Mon, 4 Mar 2024 09:56:03 -0800
From: Kees Cook <keescook@...omium.org>
To: Adrian Ratiu <adrian.ratiu@...labora.com>
Cc: Christian Brauner <brauner@...nel.org>, linux-fsdevel@...r.kernel.org,
	kernel@...labora.com, linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	Guenter Roeck <groeck@...omium.org>,
	Doug Anderson <dianders@...omium.org>, Jann Horn <jannh@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	Mike Frysinger <vapier@...omium.org>
Subject: Re: [PATCH v2] proc: allow restricting /proc/pid/mem writes

On Mon, Mar 04, 2024 at 02:35:29PM +0000, Adrian Ratiu wrote:
> Yes, easy to block and also respect page permissions (can't write
> read-only memory) as well as require ptrace access anyway by checking
> PTRACE_MODE_ATTACH_REALCREDS.

right, I don't think process_vm_writev() ignores page permissions? i.e. I
don't see where it is using FOLL_FORCE, which is one of the central
problems with /proc/$pid/mem. (Which reminds me, this is worth mentioning
more explicitly in the commit log for v3.)

-- 
Kees Cook