EFI Secure boot default keys

[AKASHI Takahiro]

On Thu, Jul 06, 2023 at 08:23:06AM +0000, Neil Jones wrote:
> >> >> Please can someone describe the format of the file needed for the default / built-in EFI secure boot keys (ubootefi.var)
> >> >>
> >> >> The only docs I have found suggest its best to enroll the keys from within u-boot onto some removable media, then copy this off and use this as the default, this is not very helpful and doesn't work for me:
> >> >>
> >> >> => fatload mmc 0:1 ${loadaddr} PK.aut
> >> >> 2053 bytes read in 18 ms (111.3 KiB/s)
> >> >> => setenv -e -nv -bs -rt -at -i ${loadaddr}:$filesize PK
> >> >> setenv - set environment variables
> >> >>
> >> >> Usage:
> >> >> setenv setenv [-f] name value ...
> >> >>     - [forcibly] set environment variable 'name' to 'value ...'
> >> >> setenv [-f] name
> >> >>     - [forcibly] delete environment variable 'name'
> >> >>
> >> >> my setenv doesn't support all the extra switches ? This is with 2022.04, all other EFI options seem to be in this release and I can boot unsigned EFI images ok.
> >> >
> >> >Please turn on CONFIG_CMD_NVEDIT_EFI when building your U-Boot.
> >> >
> >> >This option was disabled by the commit:
> >> >        commit 3b728f8728fa (tag: efi-2020-01-rc1)
> >> >        Author: Heinrich Schuchardt <xypron.glpk at gmx.de>
> >> >        Date:   Sun Oct 6 15:44:22 2019 +0200
> >> >
> >> >        cmd: disable CMD_NVEDIT_EFI by default
> >> >
> >> >The binary size of efi has grown much since in the past, though.
> >> >
> >> >-Takahiro Akashi
> >> 
> >> Thanks, I have secure boot working now. A tool to generate the ubootefi.var offline or even just a description of the file format would be very useful.
> >
> >Thank you for the suggestion. While I'd like to defer to Heinrich,
> >the C definition of the file format can be found as struct efi_var_file
> >in include/efi_variable.h
> >
> 
> Thanks!
> 
> >> I have noticed one issue when using ubootefi.var on mmc, when I switch boot order it wipes out the keys and I have to re-enrol them:
> >> 
> >> => fatls mmc 0:1
> >>      3040   ubootefi.var
> >> 
> >>  1 file(s), 0 dir(s)
> >
> >I'm not sure that secure boot related variables have been loaded
> >at this point.
> 
> This is during initial generation / enrollment of the variables
> 
> >Anyhow, please try to enable CONFIG_EFI_VARIABLES_PRESEED with
> >EFI_VAR_FILE_NAME set. Otherwise, those variables will never be
> >restored.
> >(This is another topic that are not described in doc/develop/uefi.)
> 
> I have CONFIG_EFI_VARIABLES_PRESEED working, but while generating the file ubootefi.var for the first time (without CONFIG_EFI_VARIABLES_PRESEED set) you have to follow a specific order, or the file gets overwritten eg:
> 
> Working:
> 
> efidebug boot order 1 2
> efidebug boot add -b 1 Signed mmc 0:1 /ImageSig.efi
> efidebug boot add -b 2 UnSigned mmc 0:1 /Image
> fatload mmc 0:1 ${loadaddr} PK.aut 
> setenv -e -nv -bs -rt -at -i ${loadaddr}:$filesize PK
> fatload mmc 0:1 ${loadaddr} KEK.aut                  
> setenv -e -nv -bs -rt -at -i ${loadaddr}:$filesize KEK
> fatload mmc 0:1 ${loadaddr} DB.aut                    
> setenv -e -nv -bs -rt -at -i ${loadaddr}:$filesize db 
> 
> 
> Failing:
> 
> setenv -e -nv -bs -rt -at -i ${loadaddr}:$filesize PK
> fatload mmc 0:1 ${loadaddr} KEK.aut                  
> setenv -e -nv -bs -rt -at -i ${loadaddr}:$filesize KEK
> fatload mmc 0:1 ${loadaddr} DB.aut                    
> setenv -e -nv -bs -rt -at -i ${loadaddr}:$filesize db 
> efidebug boot order 1 2   ### This command overwrites the keys just loaded

Are you sure that "env print -e" shows all the variables including
PK, KEK and db at this point?

Since I don't have enough time to examine this issue, can you please
try to trace efi_var_collect() in efi_var_file.c which is responsible
for enumerating all the non-volatile variables to be saved at each
SET_VARIABLE api call?

-Takahiro Akashi

> Cheers,
> 
> Neil
> 
> >
> >Thanks,
> >-Takahiro Akashi
> >
> >> => efidebug boot order 2 1
> >> => fatls mmc 0:1
> >>       440   ubootefi.var
> >> 
> >> (Size drops from 3040 to 440 bytes and keys have gone)
>  
> > ________________________________
> > From: AKASHI Takahiro <takahiro.akashi at linaro.org>
> > Sent: 29 June 2023 02:01
> > To: Neil Jones <neil.jones at blaize.com>
> > Cc: u-boot at lists.denx.de <u-boot at lists.denx.de>
> > Subject: Re: EFI Secure boot default keys
> > 
> > On Wed, Jun 28, 2023 at 04:26:58PM +0000, Neil Jones wrote:
> > > Please can someone describe the format of the file needed for the default / built-in EFI secure boot keys (ubootefi.var)
> > >
> > > The only docs I have found suggest its best to enroll the keys from within u-boot onto some removable media, then copy this off and use this as the default, this is not very helpful and doesn't work for me:
> > >
> > > => fatload mmc 0:1 ${loadaddr} PK.aut
> > > 2053 bytes read in 18 ms (111.3 KiB/s)
> > > => setenv -e -nv -bs -rt -at -i ${loadaddr}:$filesize PK
> > > setenv - set environment variables
> > >
> > > Usage:
> > > setenv setenv [-f] name value ...
> > >     - [forcibly] set environment variable 'name' to 'value ...'
> > > setenv [-f] name
> > >     - [forcibly] delete environment variable 'name'
> > >
> > > my setenv doesn't support all the extra switches ? This is with 2022.04, all other EFI options seem to be in this release and I can boot unsigned EFI images ok.
> > 
> > Please turn on CONFIG_CMD_NVEDIT_EFI when building your U-Boot.
> > 
> > This option was disabled by the commit:
> >         commit 3b728f8728fa (tag: efi-2020-01-rc1)
> >         Author: Heinrich Schuchardt <xypron.glpk at gmx.de>
> >         Date:   Sun Oct 6 15:44:22 2019 +0200
> > 
> >             cmd: disable CMD_NVEDIT_EFI by default
> > 
> > The binary size of efi has grown much since in the past, though.
> > 
> > -Takahiro Akashi
> > 
> > > Cheers,
> > >
> > > Neil
> > >
> > >
> > >