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

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Date:   Wed, 3 Mar 2021 17:34:01 +0100 (CET)
From:   Richard Weinberger <richard@....at>
To:     Michael Walle <michael@...le.cc>
Cc:     linux-mtd <linux-mtd@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] mtd: require write permissions for locking and badblock
 ioctls

----- 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