On Fri, Dec 03, 2021 at 12:58:13PM +0900, Masahisa Kojima wrote:
> This commit modify efi_tcg2_register() to return the
> appropriate error.
> With this fix, sandbox will not boot because efi_tcg2_register()
> fails due to some missing feature in GetCapabilities.
> So disable sandbox if EFI_TCG2_PROTOCOL is enabled.
>
> UEFI secure boot variable measurement is not directly related
> to TCG2 protocol installation, tcg2_measure_secure_boot_variable()
> is moved to the separate function.
>
> Signed-off-by: Masahisa Kojima <masahisa.koj...@linaro.org>
> ---
> include/efi_loader.h | 2 ++
> lib/efi_loader/Kconfig | 2 ++
> lib/efi_loader/efi_setup.c | 2 ++
> lib/efi_loader/efi_tcg2.c | 65 +++++++++++++++++++++++++++-----------
> 4 files changed, 53 insertions(+), 18 deletions(-)
>
> diff --git a/include/efi_loader.h b/include/efi_loader.h
> index 67c40ca57a..f4860e87fc 100644
> --- a/include/efi_loader.h
> +++ b/include/efi_loader.h
> @@ -525,6 +525,8 @@ efi_status_t efi_disk_register(void);
> efi_status_t efi_rng_register(void);
> /* Called by efi_init_obj_list() to install EFI_TCG2_PROTOCOL */
> efi_status_t efi_tcg2_register(void);
> +/* Called by efi_init_obj_list() to do initial measurement */
> +efi_status_t efi_tcg2_do_initial_measurement(void);
> /* measure the pe-coff image, extend PCR and add Event Log */
> efi_status_t tcg2_measure_pe_image(void *efi, u64 efi_size,
> struct efi_loaded_image_obj *handle,
> diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> index 700dc838dd..24f9a2bb75 100644
> --- a/lib/efi_loader/Kconfig
> +++ b/lib/efi_loader/Kconfig
> @@ -308,6 +308,8 @@ config EFI_TCG2_PROTOCOL
> bool "EFI_TCG2_PROTOCOL support"
> default y
> depends on TPM_V2
> + # Sandbox TPM currently fails on GetCapabilities needed for TCG2
> + depends on !SANDBOX
> select SHA1
> select SHA256
> select SHA384
> diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
> index 1aba71cd96..f58a4afa7f 100644
> --- a/lib/efi_loader/efi_setup.c
> +++ b/lib/efi_loader/efi_setup.c
> @@ -241,6 +241,8 @@ efi_status_t efi_init_obj_list(void)
> ret = efi_tcg2_register();
> if (ret != EFI_SUCCESS)
> goto out;
> +
> + efi_tcg2_do_initial_measurement();
> }
>
> /* Secure boot */
> diff --git a/lib/efi_loader/efi_tcg2.c b/lib/efi_loader/efi_tcg2.c
> index 5f71b188a0..6dbdd35f29 100644
> --- a/lib/efi_loader/efi_tcg2.c
> +++ b/lib/efi_loader/efi_tcg2.c
> @@ -153,6 +153,15 @@ static u16 alg_to_len(u16 hash_alg)
> return 0;
> }
>
> +static bool is_tcg2_protocol_installed(void)
> +{
> + struct efi_handler *handler;
> + efi_status_t ret;
> +
> + ret = efi_search_protocol(efi_root, &efi_guid_tcg2_protocol, &handler);
> + return ret == EFI_SUCCESS;
> +}
> +
> static u32 tcg_event_final_size(struct tpml_digest_values *digest_list)
> {
> u32 len;
> @@ -1664,6 +1673,14 @@ void tcg2_uninit(void)
> event_log.buffer = NULL;
> efi_free_pool(event_log.final_buffer);
> event_log.final_buffer = NULL;
> +
> + if (!is_tcg2_protocol_installed())
> + return;
> +
> + ret = efi_remove_protocol(efi_root, &efi_guid_tcg2_protocol,
> + (void *)&efi_tcg2_protocol);
> + if (ret != EFI_SUCCESS)
> + log_err("Failed to remove EFI TCG2 protocol\n");
> }
>
> /**
> @@ -2345,12 +2362,37 @@ error:
> return ret;
> }
>
> +/**
> + * efi_tcg2_do_initial_measurement() - do initial measurement
> + *
> + * Return: status code
> + */
> +efi_status_t efi_tcg2_do_initial_measurement(void)
> +{
> + efi_status_t ret;
> + struct udevice *dev;
> +
> + if (!is_tcg2_protocol_installed())
> + return EFI_SUCCESS;
> +
> + ret = platform_get_tpm2_device(&dev);
> + if (ret != EFI_SUCCESS)
> + goto out;
> +
Would it make more sense to return a security violation here and treat this
error similarly to patch [3/3]?
> + ret = tcg2_measure_secure_boot_variable(dev);
> + if (ret != EFI_SUCCESS)
> + goto out;
> +
> +out:
> + return ret;
> +}
> +
> /**
> * efi_tcg2_register() - register EFI_TCG2_PROTOCOL
> *
> * If a TPM2 device is available, the TPM TCG2 Protocol is registered
> *
> - * Return: An error status is only returned if adding the protocol fails.
> + * Return: status code
> */
> efi_status_t efi_tcg2_register(void)
> {
> @@ -2373,8 +2415,10 @@ efi_status_t efi_tcg2_register(void)
> }
>
> ret = efi_init_event_log();
> - if (ret != EFI_SUCCESS)
> + if (ret != EFI_SUCCESS) {
> + tcg2_uninit();
> goto fail;
> + }
>
> ret = efi_add_protocol(efi_root, &efi_guid_tcg2_protocol,
> (void *)&efi_tcg2_protocol);
> @@ -2391,24 +2435,9 @@ efi_status_t efi_tcg2_register(void)
> goto fail;
> }
>
> - ret = tcg2_measure_secure_boot_variable(dev);
> - if (ret != EFI_SUCCESS) {
> - tcg2_uninit();
> - goto fail;
> - }
> -
> return ret;
>
> fail:
> log_err("Cannot install EFI_TCG2_PROTOCOL\n");
> - /*
> - * Return EFI_SUCCESS and don't stop the EFI subsystem.
> - * That's done for 2 reasons
> - * - If the protocol is not installed the PCRs won't be extended. So
> - * someone later in the boot flow will notice that and take the
> - * necessary actions.
> - * - The TPM sandbox is limited and we won't be able to run any efi
> - * related tests with TCG2 enabled
> - */
> - return EFI_SUCCESS;
> + return ret;
> }
> --
> 2.17.1
>
Cheers
/Ilias
