On Fri, Feb 07, 2020 at 02:14:37PM +0900, AKASHI Takahiro wrote:
A small text in docs/uefi/uefi.rst was added to explain how we can configure and utilise UEFI secure boot feature on U-Boot.
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org
doc/uefi/uefi.rst | 77 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+)
diff --git a/doc/uefi/uefi.rst b/doc/uefi/uefi.rst index a8fd886d6b5e..98cd770aefe5 100644 --- a/doc/uefi/uefi.rst +++ b/doc/uefi/uefi.rst @@ -97,6 +97,83 @@ Below you find the output of an example session starting GRUB::
See doc/uImage.FIT/howto.txt for an introduction to FIT images.
+Configuring UEFI secure boot +~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+UEFI specification[1] defines a secure way of executing UEFI images +by verifying a signature (or message digest) of image with certificates. +This feature on U-Boot is enabled with::
- CONFIG_UEFI_SECURE_BOOT=y
+To make the boot sequence safe, you need to establish a chain of trust; +In UEFI secure boot, you can make it with the UEFI variables, "PK" +(Platform Key), "KEK" (Key Exchange Keys), "db" (white list database) +and "dbx" (black list database).
+There are many online documents that describe what UEFI secure boot is +and how it works. Please consult some of them for details.
+Here is a simple example that you can follow for your initial attempt +(Please note that the actual steps would absolutely depend on your system +and environment.):
+1. Install utility commands on your host
- openssl
- efitools
- sbsigntool
+2. Create signing keys and key database files on your host
- for PK::
$ openssl req -x509 -sha256 -newkey rsa:2048 -subj /CN=TEST_PK/ \-keyout PK.key -out PK.crt -nodes -days 365$ cert-to-efi-sig-list -g 11111111-2222-3333-4444-123456789abc \PK.crt PK.esl;$ sign-efi-sig-list -c PK.crt -k PK.key PK PK.esl PK.auth- for KEK::
$ openssl req -x509 -sha256 -newkey rsa:2048 -subj /CN=TEST_KEK/ \-keyout KEK.key -out KEK.crt -nodes -days 365$ cert-to-efi-sig-list -g 11111111-2222-3333-4444-123456789abc \KEK.crt KEK.esl$ sign-efi-sig-list -c PK.crt -k PK.key KEK KEK.esl KEK.auth- for db::
$ openssl req -x509 -sha256 -newkey rsa:2048 -subj /CN=TEST_db/ \-keyout db.key -out db.crt -nodes -days 365$ cert-to-efi-sig-list -g 11111111-2222-3333-4444-123456789abc \db.crt db.esl$ sign-efi-sig-list -c KEK.crt -k KEK.key db db.esl db.auth- Copy *.auth to media, say mmc, that is accessible from U-Boot.
+3. Sign an image with one key in "db" on your host::
- $ sbsign --key db.key --cert db.crt helloworld.efi
+4. Install keys on your board::
- ==> fatload mmc 0:1 <tmpaddr> PK.auth
- ==> setenv -e -nv -bs -rt -at -i <tmpaddr>,$filesize PK
- ==> fatload mmc 0:1 <tmpaddr> KEK.auth
- ==> setenv -e -nv -bs -rt -at -i <tmpaddr>,$filesize KEK
- ==> fatload mmc 0:1 <tmpaddr> db.auth
- ==> setenv -e -nv -bs -rt -at -i <tmpaddr>,$filesize db
+5. Set up boot parameters on your board::
- ==> efidebug boot add 1 HELLO mmc 0:1 /helloworld.efi.signed ""
+Then your board runs that image from Boot manager (See below). +You can also try this sequence by running Pytest, test_efi_secboot, +on sandbox::
- $ cd <U-Boot source directory>
- $ pytest.py test/py/tests/test_efi_secboot/test_signed.py --bd sandbox
Executing the boot manager
-- 2.24.0
Acked-by: Ilias Apalodimas ilias.apalodimas@linaro.org