linux-kernel - Re: [PATCH v2 1/3] nvmem: core: make default user binary file root-access only

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Date:	Wed, 07 Oct 2015 14:18:47 +0100
From:	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To:	Greg KH <gregkh@...uxfoundation.org>
CC:	maxime.ripard@...e-electrons.com, linux-kernel@...r.kernel.org,
	andrew@...n.ch, wxt@...k-chips.com, stefan.wahren@...e.com,
	pantelis.antoniou@...sulko.com, maitysanchayan@...il.com,
	p.zabel@...gutronix.de, s.hauer@...gutronix.de,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 1/3] nvmem: core: make default user binary file root-access
 only



On 07/10/15 13:55, Greg KH wrote:
> On Wed, Oct 07, 2015 at 12:00:47PM +0100, Srinivas Kandagatla wrote:
>> As required by many providers like at24/at25/mxs-ocotp/qfprom and may be
>> other providers would want to allow root-only to read the nvmem content.
>> So making the defaults to be root-only access would address the request
>> and also provide flexibility to providers to specify there own permissions
>> on top of the root-only using the perm flag in nvmem_config.
>
> Eeek, no, don't mess with different permissions, that's not ok, be
> consistent and only allow root write access, that's why we have static
> build-time checks to ensure you get this correct and do not accidentally
> let a "normal" user access to things they shouldn't have access to.
Thanks for your inputs,

Code as it is in mainline would provide a write permission to root-only 
and read to all the group.

Fixing/removing the group read permissions should stop normal user 
accessing the binary file.


--srini
>
>> Making this dynamic did cut down lot of static binary attributes in the
>> code.
>
> Nothing wrong with static binary attributes, please use them instead.
>
> thanks,
>
> greg k-h
>
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