Hi Ilias,
On Tue, 20 Dec 2022 at 15:56, Ilias Apalodimas
<ilias.apalodi...@linaro.org> wrote:
>
> On Tue, Dec 20, 2022 at 12:12:56AM +0900, Masahisa Kojima wrote:
> > The signed null key with authenticated header is used to clear
> > the PK, KEK, db and dbx. When CONFIG_EFI_MM_COMM_TEE is enabled
> > (StMM and OP-TEE based RPMB storage is used as the EFI variable
> > storage), clearing KEK, db and dbx by enrolling a signed null
> > key does not work as expected if EFI_VARIABLE_APPEND_WRITE
> > attritube is set.
> >
> > This commit checks the selected file is null key, then
> > EFI_VARIABLE_APPEND_WRITE attibute will not be used for the null key.
> >
> > Signed-off-by: Masahisa Kojima <masahisa.koj...@linaro.org>
> > ---
> > cmd/eficonfig_sbkey.c | 40 ++++++++++++++++++++++++++++++++++++++--
> > 1 file changed, 38 insertions(+), 2 deletions(-)
> >
> > diff --git a/cmd/eficonfig_sbkey.c b/cmd/eficonfig_sbkey.c
> > index 6e0bebf1d4..bd2671bf8f 100644
> > --- a/cmd/eficonfig_sbkey.c
> > +++ b/cmd/eficonfig_sbkey.c
> > @@ -72,6 +72,30 @@ static bool file_have_auth_header(void *buf, efi_uintn_t
> > size)
> > return true;
> > }
> >
> > +/**
> > + * file_is_null_key() - check the file is an authenticated and signed null
> > key
> > + * @auth: pointer to the file
> > + * @size: file size
> > + * @null_key: pointer to store the result
> > + * Return: status code
> > + */
> > +static efi_status_t file_is_null_key(struct efi_variable_authentication_2
> > *auth,
> > + efi_uintn_t size, bool *null_key)
> > +{
> > + efi_status_t ret = EFI_SUCCESS;
> > +
> > + if (size < (sizeof(auth->time_stamp) + auth->auth_info.hdr.dwLength))
> > + return EFI_INVALID_PARAMETER;
> > +
> > + size -= (sizeof(auth->time_stamp) + auth->auth_info.hdr.dwLength);
> > + if (size == 0) /* No payload */
>
> s/size == 0/!size
OK.
Thank you for your review.
Regards,
Masahisa Kojima
>
> > + *null_key = true;
> > + else
> > + *null_key = false;
> > +
> > + return ret;
> > +}
> > +
> > /**
> > * eficonfig_process_enroll_key() - enroll key into signature database
> > *
> > @@ -84,6 +108,7 @@ static efi_status_t eficonfig_process_enroll_key(void
> > *data)
> > char *buf = NULL;
> > efi_uintn_t size;
> > efi_status_t ret;
> > + bool null_key = false;
> > struct efi_file_handle *f = NULL;
> > struct efi_device_path *full_dp = NULL;
> > struct eficonfig_select_file_info file_info;
> > @@ -149,13 +174,24 @@ static efi_status_t eficonfig_process_enroll_key(void
> > *data)
> > goto out;
> > }
> >
> > + ret = file_is_null_key((struct efi_variable_authentication_2 *)buf,
> > + size, &null_key);
> > + if (ret != EFI_SUCCESS) {
> > + eficonfig_print_msg("ERROR! Invalid file format.");
> > + goto out;
> > + }
> > +
> > attr = EFI_VARIABLE_NON_VOLATILE |
> > EFI_VARIABLE_BOOTSERVICE_ACCESS |
> > EFI_VARIABLE_RUNTIME_ACCESS |
> > EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS;
> >
> > - /* PK can enroll only one certificate */
> > - if (u16_strcmp(data, u"PK")) {
> > + /*
> > + * PK can enroll only one certificate.
> > + * The signed null key is used to clear KEK, db and dbx.
> > + * EFI_VARIABLE_APPEND_WRITE attribute must not be set in these cases.
> > + */
> > + if (u16_strcmp(data, u"PK") && !null_key) {
> > efi_uintn_t db_size = 0;
> >
> > /* check the variable exists. If exists, add APPEND_WRITE
> > attribute */
> > --
> > 2.17.1
> >
>
> Reviewed-by: Ilias Apalodimas <ilias.apalodi...@linaro.org>
>
