[U-Boot] [PATCH 4/6] spl: mmc: support loading i.MX container format file

Wed May 22 06:02:52 UTC 2019

Hi Peng,

> Hi Lukasz,
> 
> > -----Original Message-----
> > From: Lukasz Majewski [mailto:lukma at denx.de]
> > Sent: 2019年5月21日 16:33
> > To: Peng Fan <peng.fan at nxp.com>
> > Cc: Marek Vasut <marex at denx.de>; Marek Vasut
> > <marek.vasut at gmail.com>; Simon Glass <sjg at chromium.org>;
> > u-boot at lists.denx.de; Tien Fong Chee <tien.fong.chee at intel.com>;
> > York Sun <york.sun at nxp.com>; dl-uboot-imx <uboot-imx at nxp.com>
> > Subject: Re: [U-Boot] [PATCH 4/6] spl: mmc: support loading i.MX
> > container format file
> > 
> > Hi Peng,
> >   
> > > > Subject: Re: [U-Boot] [PATCH 4/6] spl: mmc: support loading i.MX
> > > > container format file
> > > >
> > > > On 5/21/19 4:55 AM, Peng Fan wrote:
> > > > [...]
> > > >  
> > > > >>>>> I do not know how other SoC vendor did FIT hardware secure
> > > > >>>>> boot, please share you have any information.  
> > > > >>>>
> > > > >>>> The SPL can be in the custom format, but then can load
> > > > >>>> fitImage with the next stage(s), right ?  
> > > > >>>
> > > > >>> I am not able to follow you, could you share more details?  
> > > > >>
> > > > >> Wrap the SPL into this custom format and then have the SPL
> > > > >> load/authenticate fitImage with the rest (U-Boot, Linux, DTB
> > > > >> etc). Would that work ?  
> > > > >
> > > > > It not work.
> > > > > We already wrap SPL in i.MX container format, this patchset
> > > > > is to let SPL could load the 2nd container file which contains
> > > > > U-Boot/DTB/OP-TEE/ATF.  If we let SPL load a fitimage which
> > > > > contains (U-Boot/DTB and etc), it could not pass secure boot
> > > > > authentication, because ROM not know fitimage, it only know
> > > > > i.MX container format.  
> > > >
> > > > It's not bootrom that authenticates the next stage, it's U-Boot
> > > > SPL. BootROM already authenticated and started the U-Boot SPL,
> > > > so that's a trusted code. Now this trusted code can
> > > > authenticate and start the next stage (U-Boot, ATF, OpTee OS,
> > > > etc) ; the BootROM is already out of the picture at this
> > > > point.  
> > >
> > > Sorry for not clear. On i.MX8, SCFW (a runtime firmware )exports
> > > API for others to use, sc_seco_authenticate is the API that used
> > > for authentication. I could not share more information about this
> > > API works inside SCFW and ROM. sc_err_t
> > > sc_seco_authenticate(sc_ipc_t ipc, sc_seco_auth_cmd_t cmd,
> > > sc_faddr_t addr)
> > >
> > > SPL will call this API, one parameter is address which needs a
> > > container image there.  
> > 
> > Please consider following scenario (I think that this is in sync
> > with Marek's point):
> > 
> > 1. You wrap SPL into i.MX8 "container", so the SPL would be
> > recognised an checked by secure code in ROM.
> > 
> > 2. Then we do have SPL "trusted". It is up to SPL to:
> > 
> > 2.1. Use its private key to check u-boot, dtb, etc embedded into
> > FitImage (as written here: ./doc/uImage.FIT/verified-boot.txt).
> > 
> > 2.2. Use crypto engine (it's API) with fused keys to speed-up the
> > process of boot (by HW support to check the binary). Such approach
> > is in i.MX6Q.  
> 
> I suppose you talking HAB.

Yes. As described here:

https://www.nxp.com/docs/en/application-note/AN4581.pdf

> 
> > 
> > 
> > By using above approach we do have the NXP's "container" format
> > only seen in the SPL (which is OK, as for example Samsung does
> > similar thing with FBL/BL1). When SPL is "trused" we may use
> > available facilities.  
> 
> The issue to me is that sc_seco_authenticate could not take a FIT
> image as input.

Is the sc_seco_authenticate an API accessible from SPL, U-Boot proper
or Linux crypro engine driver?

Or is it just the function executed by ROM on the very beginning to
load SPL?

> 
> If I switch to FIT, I need to use FIT to wrap a container image, it
> does not make sense to me.

Please correct me if I'm wrong, but isn't the container image only
needed to wrap SPL?

In which other cases the container image is needed in U-Boot proper or
Linux kernel?

> 
> Thanks,
> Peng.
> >   
> > >  
> > > >  
> > > > > For authentication, we always let ROM to authenticate
> > > > > including SPL authenticating U-Boot, so we need pass an image
> > > > > to ROM that ROM could recognize when SPL booting 2nd image.  
> > > >
> > > > Shouldn't the CPU have some sort of facility, like a crypto
> > > > engine, which authenticates whatever blob with the right
> > > > signature against a key burned into the CPU ? If so, then you
> > > > would just implement a crypto driver and pass the blob and
> > > > signature to it. I suspect that's how it should work, how else
> > > > would Linux be able to make use of these secure bits if it
> > > > cannot call the bootrom anymore ?  
> > >
> > > sc_seco_authenticate on i.MX8 will always be available. It is
> > > exported by a runtime firmware running on a Cortex-M core inside
> > > i.MX8. The API will do authentication, its accepts container
> > > format image as input and no other format.
> > >
> > > Thanks,
> > > Peng.
> > >  
> > > >
> > > > --
> > > > Best regards,
> > > > Marek Vasut  
> > > _______________________________________________
> > > U-Boot mailing list
> > > U-Boot at lists.denx.de
> > > https://lists.denx.de/listinfo/u-boot  
> > 
> > 
> > 
> > 
> > Best regards,
> > 
> > Lukasz Majewski
> > 
> > --
> > 
> > DENX Software Engineering GmbH,      Managing Director: Wolfgang
> > Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell,
> > Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email:
> > lukma at denx.de  

Best regards,

Lukasz Majewski

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma at denx.de
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 488 bytes
Desc: OpenPGP digital signature
URL: <http://lists.denx.de/pipermail/u-boot/attachments/20190522/f055de0b/attachment.sig>