[U-Boot] [PATCH 12/16] cmd: env: use appropriate guid for authenticated UEFI variable

Heinrich Schuchardt
2019-11-16T20:10:35Z

On 11/13/19 1:53 AM, AKASHI Takahiro wrote:
> A signature database variable is associated with a specific guid.
> For convenience, if user doesn't supply any guid info, "env set|print -e"
> should complement it.

If secure boot is enforced, users should not be able to change any
security relevant variables. Instead we need a way to compile the
security relevant data into the U-Boot binary and add a signature to the
U-Boot binary which can be checked by the primary boot loader.

Best regards

Heinrich

>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> ---
> cmd/nvedit_efi.c | 18 ++++++++++++++----
> 1 file changed, 14 insertions(+), 4 deletions(-)
>
> diff --git a/cmd/nvedit_efi.c b/cmd/nvedit_efi.c
> index 8ea0da01283f..579cf430593c 100644
> --- a/cmd/nvedit_efi.c
> +++ b/cmd/nvedit_efi.c
> @@ -41,6 +41,11 @@ static const struct {
> } efi_guid_text[] = {
> /* signature database */
> {EFI_GLOBAL_VARIABLE_GUID, "EFI_GLOBAL_VARIABLE_GUID"},
> + {EFI_IMAGE_SECURITY_DATABASE_GUID, "EFI_IMAGE_SECURITY_DATABASE_GUID"},
> + /* certificate type */
> + {EFI_CERT_SHA256_GUID, "EFI_CERT_SHA256_GUID"},
> + {EFI_CERT_X509_GUID, "EFI_CERT_X509_GUID"},
> + {EFI_CERT_TYPE_PKCS7_GUID, "EFI_CERT_TYPE_PKCS7_GUID"},
> };
>
> /* "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" */
> @@ -525,9 +530,9 @@ int do_env_set_efi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
> if (*ep != ',')
> return CMD_RET_USAGE;
>
> + /* 0 should be allowed for delete */
> size = simple_strtoul(++ep, NULL, 16);
> - if (!size)
> - return CMD_RET_FAILURE;
> +
> value_on_memory = true;
> } else if (!strcmp(argv[0], "-v")) {
> verbose = true;
> @@ -539,8 +544,13 @@ int do_env_set_efi(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
> return CMD_RET_USAGE;
>
> var_name = argv[0];
> - if (default_guid)
> - guid = efi_global_variable_guid;
> + if (default_guid) {
> + if (!strcmp(var_name, "db") || !strcmp(var_name, "dbx") ||
> + !strcmp(var_name, "dbt"))
> + guid = efi_guid_image_security_database;
> + else
> + guid = efi_global_variable_guid;
> + }
>
> if (verbose) {
> printf("GUID: %s\n", efi_guid_to_str((const efi_guid_t *)
>