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@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
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@linaro.org Sent: 29 June 2023 02:01 To: Neil Jones neil.jones@blaize.com Cc: u-boot@lists.denx.de u-boot@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@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