linux-kernel - Re: printk: Add kernel parameter to disable writes to /dev/kmsg

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Message-ID: <5720A1B3.9020604@gmail.com>
Date:	Wed, 27 Apr 2016 07:25:39 -0400
From:	"Austin S. Hemmelgarn" <ahferroin7@...il.com>
To:	Steven Rostedt <rostedt@...dmis.org>, Pavel Machek <pavel@....cz>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Borislav Petkov <bp@...en8.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: printk: Add kernel parameter to disable writes to /dev/kmsg

On 2016-04-26 15:47, Steven Rostedt wrote:
> On Tue, 26 Apr 2016 20:44:58 +0200
> Pavel Machek <pavel@....cz> wrote:
>
>>> I simply propose a way to let us kernel developers keep user space from
>>> interfering, by adding a new kernel command line parameter that will
>>> disable writing to /dev/kmsg. Any attempt to open the file in write
>>> mode will return a -EPERM error.
>>
>> chmod 400 /dev/kmsg? With udev, it should be possible to make it persistent...
>
> But this opened while initramdisk is used. I'm thinking this wont work,
> or does udev run before main root is mounted?
>
It does, but I don't think it runs before journald on systemd systems...

So it probably still wouldn't work.