Re: [PATCH] mtd: require write permissions for locking and badblock ioctls

From: Richard Weinberger <richard@nod.at>
To: Michael Walle <michael@walle.cc>
Cc: linux-mtd <linux-mtd@lists.infradead.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Miquel Raynal <miquel.raynal@bootlin.com>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] mtd: require write permissions for locking and badblock ioctls
Date: Wed, 3 Mar 2021 17:34:01 +0100 (CET)	[thread overview]
Message-ID: <675291050.42876.1614789241828.JavaMail.zimbra@nod.at> (raw)
In-Reply-To: <040cf2058fe4cf5e63dbff534582881a@walle.cc>

----- Ursprüngliche Mail -----
>>> Thanks for auditing the rest of these from my original patch.  If this
>>> is ok with userspace tools, it's fine with me, but I don't even have
>>> this hardware to test with :)
>> 
>> That's my fear. Michael, did you verify?
> 
> I don't know any tools except the mtd-utils. So no.

openwrt folks have their own tooling, Anrdoid too.

>> In general you need to be root to open these device files.
>> So, I don't see a security problem here.
> 
> Then this begs the question, why is this check there in
> the first place?

I fear historical reasons.
As soon you can open the device node you can do evil things.

> This come up because I was adding a OTPERASE which
> was suggested that is was a "dangerous" command. So I
> was puzzled why the ones above are considered "safe" ;)

:-)

Thanks,
//richard