Date: Sat, 3 Sep 2016 19:17:17 +0200 From: Emmanuel Vadot <manu@bidouilliste.com> To: Jared McNeill <jmcneill@invisible.ca> Cc: Oliver Pinter <oliver.pinter@hardenedbsd.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r305354 - head/sys/arm/allwinner Message-ID: <20160903191717.437e45cb8d0d612211bdc0c5@bidouilliste.com> In-Reply-To: <alpine.DEB.2.11.1609031358300.641@dis.invisible.ca> References: <201609031528.u83FS91u017461@repo.freebsd.org> <CAPQ4ffs%2BdexyyewdwLg1Hp1j30Yn5Lfu5uajzVy99sgwBjNXAA@mail.gmail.com> <alpine.DEB.2.11.1609031358300.641@dis.invisible.ca>
next in thread | previous in thread | raw e-mail | index | archive | help
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@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@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@freebsd.org mailing list > >> https://lists.freebsd.org/mailman/listinfo/svn-src-head > >> To unsubscribe, send any mail to "svn-src-head-unsubscribe@freebsd.org" > >> > > > > -- Emmanuel Vadot
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20160903191717.437e45cb8d0d612211bdc0c5>