svn commit: r305354 - head/sys/arm/allwinner

[Oliver Pinter]

Hi!

Thanks for explanation. The feature's name is very misleading...


On 9/3/16, Jared McNeill <jmcneill at invisible.ca> wrote:
> Hi Oliver --
>
> It's really just a serial number. The Allwinner A20 datasheet refers to it
> as a root key, later ones such as A83T refer to it as chip ID. U-Boot
> uses the same process to generate MAC addresses for all Allwinner boards.
>
> Cheers,
> Jared
>
>
> On Sat, 3 Sep 2016, Oliver Pinter wrote:
>
>> Hi!
>>
>> On 9/3/16, Jared McNeill <jmcneill at freebsd.org> wrote:
>>> Author: jmcneill
>>> Date: Sat Sep  3 15:28:09 2016
>>> New Revision: 305354
>>> URL: https://svnweb.freebsd.org/changeset/base/305354
>>>
>>> Log:
>>>   Use the root key in the Security ID EFUSE (when valid) to generate a
>>>   MAC address instead of creating a random one each boot.
>>
>> Could you please describe a little more about this root key? What is
>> it? What's the main purpose? Is is a crypto root key?
>>
>>>
>>> Modified:
>>>   head/sys/arm/allwinner/if_awg.c
>>>
>>> Modified: head/sys/arm/allwinner/if_awg.c
>>> ==============================================================================
>>> --- head/sys/arm/allwinner/if_awg.c	Sat Sep  3 15:26:28 2016	(r305353)
>>> +++ head/sys/arm/allwinner/if_awg.c	Sat Sep  3 15:28:09 2016	(r305354)
>>> @@ -62,6 +62,7 @@ __FBSDID("$FreeBSD$");
>>>  #include <dev/ofw/ofw_bus_subr.h>
>>>
>>>  #include <arm/allwinner/if_awgreg.h>
>>> +#include <arm/allwinner/aw_sid.h>
>>>  #include <dev/mii/mii.h>
>>>  #include <dev/mii/miivar.h>
>>>
>>> @@ -1277,6 +1278,7 @@ awg_get_eaddr(device_t dev, uint8_t *ead
>>>  {
>>>  	struct awg_softc *sc;
>>>  	uint32_t maclo, machi, rnd;
>>> +	u_char rootkey[16];
>>>
>>>  	sc = device_get_softc(dev);
>>>
>>> @@ -1285,9 +1287,19 @@ awg_get_eaddr(device_t dev, uint8_t *ead
>>>
>>>  	if (maclo == 0xffffffff && machi == 0xffff) {
>>>  		/* MAC address in hardware is invalid, create one */
>>> -		rnd = arc4random();
>>> -		maclo = 0x00f2 | (rnd & 0xffff0000);
>>> -		machi = rnd & 0xffff;
>>> +		if (aw_sid_get_rootkey(rootkey) == 0 &&
>>> +		    (rootkey[3] | rootkey[12] | rootkey[13] | rootkey[14] |
>>> +		     rootkey[15]) != 0) {
>>> +			/* MAC address is derived from the root key in SID */
>>> +			maclo = (rootkey[13] << 24) | (rootkey[12] << 16) |
>>> +				(rootkey[3] << 8) | 0x02;
>>> +			machi = (rootkey[15] << 8) | rootkey[14];
>>> +		} else {
>>> +			/* Create one */
>>> +			rnd = arc4random();
>>> +			maclo = 0x00f2 | (rnd & 0xffff0000);
>>> +			machi = rnd & 0xffff;
>>> +		}
>>>  	}
>>>
>>>  	eaddr[0] = maclo & 0xff;
>>> _______________________________________________
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>>>
>>
>>
>