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

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Date:	Mon, 25 Apr 2016 20:32:50 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Steven Rostedt <rostedt@...dmis.org>
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>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] printk: Add kernel parameter to disable writes to
 /dev/kmsg

On Mon, Apr 25, 2016 at 01:08:53PM -0400, Steven Rostedt wrote:
> [ Sorry for the resend, I forgot to add "[PATCH]" to the subject, which
>   may make this fail filters. ]
> 
> Over the weekend my server was acting funny. The display wasn't working
> well, and I assumed that a driver was going bad. I went to look at the
> kernel dmesg, but the buffer only had the following over and over:

...

> +	disable_devkmsg_write
> +			Disable writing to /dev/kmsg. This prevents user space
> +			tools from writing into the kernel printk buffers.
> +			When set, opening /dev/kmsg for write mode will return
> +			-EPERM.

I like the general idea.

Perhaps can call that param "printk.disable_devkmsg" or so with the
proper namespace and in light of printk.always_kmsg_dump=...

Anyway, just my 2¢.

Thanks.

-- 
Regards/Gruss,
    Boris.

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