svn commit: r305354 - head/sys/arm/allwinner
Emmanuel Vadot
manu at bidouilliste.com
Sat Sep 3 17:24:03 UTC 2016
I'll add that everybody uses this as a serial number. Since thoses are
efuses, you can't change it unless a specific voltage is applied to a
certain pin (which is tied to GND on every board), but no one have tried
to do that.
There might be some way do restrict reading that key a
there is also some configuration fuses but the documentation doesn't
say much about this peripheral.
You can check http://linux-sunxi.org/SID for (a little) more
information.
On Sat, 3 Sep 2016 14:06:37 -0300 (ADT)
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;
> >> _______________________________________________
> >> svn-src-head at freebsd.org mailing list
> >> https://lists.freebsd.org/mailman/listinfo/svn-src-head
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> >>
> >
> >
--
Emmanuel Vadot
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