linux-kernel - Re: [PATCH v9 0/9] Add simple NVMEM Framework via regmap.

Open Source and information security mailing list archives

Date:	Mon, 10 Aug 2015 13:24:38 +0200 (CEST)
From:	Stefan Wahren <stefan.wahren@...e.com>
To:	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
	Andrew Lunn <andrew@...n.ch>
Cc:	wxt@...k-chips.com, linux-api@...r.kernel.org,
	Rob Herring <robh+dt@...nel.org>, sboyd@...eaurora.org,
	arnd@...db.de, linux-arm-kernel@...ts.infradead.org,
	khilman@...nel.org, s.hauer@...gutronix.de,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	mporter@...sulko.com, pantelis.antoniou@...sulko.com,
	devicetree@...r.kernel.org, Mark Brown <broonie@...nel.org>,
	maitysanchayan@...il.com, p.zabel@...gutronix.de
Subject: Re: [PATCH v9 0/9] Add simple NVMEM Framework via regmap.

Hi Srinivas,
hi Andrew,

[add Sanchayan and Philipp]

> Srinivas Kandagatla <srinivas.kandagatla@...aro.org> hat am 10. August 2015 um
> 12:37 geschrieben:
>
>
> Hi Andrew,
>
> On 09/08/15 16:19, Andrew Lunn wrote:
> > Hi Srinivas
> >
> > The AT24 eeprom driver contains the comment:
> >
> > /*
> > * Export the EEPROM bytes through sysfs, since that's convenient.
> > * By default, only root should see the data (maybe passwords etc)
> > */
> >
> > and as you would expect from this:
> >
> > # ls -l
> > ./devices/platform/soc/soc:aips-bus@...00000/40066000.i2c/i2c-0/0-0050/eeprom
> > -rw------- 1 root root 512 Aug 9 10:16
> > ./devices/platform/soc/soc:aips-bus@...00000/40066000.i2c/i2c-0/0-0050/eeprom
> >
> > The AT25 and the MAX6875 driver are the same.
> >
> > However nvmem has different defaults:
> >
> > # ls -l
> > ./devices/platform/soc/soc:aips-bus@...00000/40066000.i2c/i2c-0/0-0050/0-00500/nvmem
> > -rw-r--r-- 1 root root 0 Aug 9 10:16
> > ./devices/platform/soc/soc:aips-bus@...00000/40066000.i2c/i2c-0/0-0050/0-00500/nvmem
> >
> Yes, nvmem by default sets the read permission for everyone S_IRUGO.
> Which was the most common use case.

i can only speak for mxs-ocotp, but root-only access is sufficient.

>
> > Has this been considered and discussed?
> Thanks for bringing this up, No, we did not discuss this explicitly, but
> it should not be an issue to accommodate this. Provider still have
> flexibility to configure such things.

IMHO it would better the default settings of the framework would be compatible
and same restrictive as the eeprom drivers.

In case a provider needs more privileges, it should be his job.

>
> As a first patchset we wanted to keep the framework simple and add
> features as we move on.

That's true, but it's an ABI too. So changing default settings soon is better.

Regards
Stefan

>
> Thanks,
> srini
> >
> > Thanks
> > Andrew
> >
>
> _______________________________________________
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