Re: [RFC PATCH v2 6/8] FWU: Add boot time checks as highlighted by the FWU specification

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

Sughosh,

On Sun, Dec 19, 2021 at 12:36:03PM +0530, Sughosh Ganu wrote:
> The FWU Multi Bank Update specification requires the Update Agent to
> carry out certain checks at the time of platform boot. The Update
> Agent is the component which is responsible for updating the firmware
> components and maintaining and keeping the metadata in sync.
> 
> The spec requires that the Update Agent perform the following checks
> at the time of boot
> * Sanity check of both the metadata copies maintained by the platform.
> * Get the boot index passed to U-Boot by the prior stage bootloader
>   and use this value for metadata bookkeeping.
> * Check if the system is booting in Trial State. If the system boots
>   in the Trial State for more than a specified number of boot counts,
>   change the Active Bank to be booting the platform from.
> 
> Add these checks in the board initialisation sequence, invoked after
> relocation.
> 
> Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
> ---
> Changes since V1:
> * Define a funtion fwu_update_checks_pass to do the checks
>   before initiating the update
> * Log the status of the boottime checks using boottime_check
>   variable and allow system to boot instead of hanging the
>   platform(fwu_boottime_checks)
> 
>  common/board_r.c      |   6 ++
>  include/fwu.h         |   3 +
>  lib/fwu_updates/fwu.c | 163 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 172 insertions(+)
>  create mode 100644 lib/fwu_updates/fwu.c
> 
> diff --git a/common/board_r.c b/common/board_r.c
> index 31a59c585a..81678870b9 100644
> --- a/common/board_r.c
> +++ b/common/board_r.c
> @@ -78,6 +78,9 @@
>  #ifdef CONFIG_EFI_SETUP_EARLY
>  #include <efi_loader.h>
>  #endif
> +#ifdef CONFIG_FWU_MULTI_BANK_UPDATE
> +#include <fwu.h>
> +#endif
>  
>  DECLARE_GLOBAL_DATA_PTR;
>  
> @@ -805,6 +808,9 @@ static init_fnc_t init_sequence_r[] = {
>  #endif
>  #ifdef CONFIG_EFI_SETUP_EARLY
>  	(init_fnc_t)efi_init_obj_list,
> +#endif
> +#ifdef CONFIG_FWU_MULTI_BANK_UPDATE
> +	fwu_boottime_checks,
>  #endif

Maybe I don't understand your code well.
Why do you want to call fwu_boottime_checks() here?
Why not in CONFIG_EFI_CAPSULE_UPDATE_EARLY (i.e. efi_launch_capsules()
in main_loop())?

-Takahiro Akashi

>  	run_main_loop,
>  };
> diff --git a/include/fwu.h b/include/fwu.h
> index 5ba437798d..2d2e674d6a 100644
> --- a/include/fwu.h
> +++ b/include/fwu.h
> @@ -16,6 +16,9 @@
>  	EFI_GUID(0x8a7a84a0, 0x8387, 0x40f6, 0xab, 0x41, \
>  		 0xa8, 0xb9, 0xa5, 0xa6, 0x0d, 0x23)
>  
> +int fwu_boottime_checks(void);
> +u8 fwu_update_checks_pass(void);
> +
>  int fwu_get_active_index(u32 *active_idx);
>  int fwu_update_active_index(u32 active_idx);
>  int fwu_get_image_alt_num(efi_guid_t image_type_id, u32 update_bank,
> diff --git a/lib/fwu_updates/fwu.c b/lib/fwu_updates/fwu.c
> new file mode 100644
> index 0000000000..e964f9b0b1
> --- /dev/null
> +++ b/lib/fwu_updates/fwu.c
> @@ -0,0 +1,163 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (c) 2021, Linaro Limited
> + */
> +
> +#include <efi.h>
> +#include <efi_loader.h>
> +#include <efi_variable.h>
> +#include <fwu.h>
> +#include <fwu_mdata.h>
> +#include <malloc.h>
> +
> +#include <linux/errno.h>
> +#include <linux/types.h>
> +
> +static u8 trial_state = 0;
> +static u8 boottime_check = 0;
> +
> +static int fwu_trial_state_check(void)
> +{
> +	int ret, i;
> +	efi_status_t status;
> +	efi_uintn_t var_size;
> +	u16 trial_state_ctr;
> +	u32 nimages, active_bank, var_attributes, active_idx;
> +	struct fwu_mdata *mdata = NULL;
> +	struct fwu_image_entry *img_entry;
> +	struct fwu_image_bank_info *img_bank_info;
> +
> +	ret = fwu_get_mdata(&mdata);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = 0;
> +	nimages = CONFIG_FWU_NUM_IMAGES_PER_BANK;
> +	active_bank = mdata->active_index;
> +	img_entry = &mdata->img_entry[0];
> +	for (i = 0; i < nimages; i++) {
> +		img_bank_info = &img_entry[i].img_bank_info[active_bank];
> +		if (!img_bank_info->accepted) {
> +			trial_state = 1;
> +			break;
> +		}
> +	}
> +
> +	if (trial_state) {
> +		var_size = (efi_uintn_t)sizeof(trial_state_ctr);
> +		log_info("System booting in Trial State\n");
> +		var_attributes = EFI_VARIABLE_NON_VOLATILE |
> +			EFI_VARIABLE_BOOTSERVICE_ACCESS |
> +			EFI_VARIABLE_RUNTIME_ACCESS;
> +		status = efi_get_variable_int(L"TrialStateCtr",
> +					      &efi_global_variable_guid,
> +					      &var_attributes,
> +					      &var_size, &trial_state_ctr,
> +					      NULL);
> +		if (status != EFI_SUCCESS) {
> +			log_err("Unable to read TrialStateCtr variable\n");
> +			ret = -1;
> +			goto out;
> +		}
> +
> +		++trial_state_ctr;
> +		if (trial_state_ctr > CONFIG_FWU_TRIAL_STATE_CNT) {
> +			log_info("Trial State count exceeded. Revert back to previous_active_index\n");
> +			active_idx = mdata->active_index;
> +			ret = fwu_revert_boot_index();
> +			if (ret < 0) {
> +				log_err("Unable to revert active_index\n");
> +				goto out;
> +			}
> +
> +			trial_state_ctr = 0;
> +			status = efi_set_variable_int(L"TrialStateCtr",
> +						      &efi_global_variable_guid,
> +						      var_attributes,
> +						      0,
> +						      &trial_state_ctr, false);
> +			if (status != EFI_SUCCESS) {
> +				log_err("Unable to clear TrialStateCtr variable\n");
> +				ret = -1;
> +				goto out;
> +			}
> +		} else {
> +			status = efi_set_variable_int(L"TrialStateCtr",
> +						      &efi_global_variable_guid,
> +						      var_attributes,
> +						      var_size,
> +						      &trial_state_ctr, false);
> +			if (status != EFI_SUCCESS) {
> +				log_err("Unable to increment TrialStateCtr variable\n");
> +				ret = -1;
> +				goto out;
> +			} else {
> +				ret = 0;
> +			}
> +		}
> +	}
> +
> +out:
> +	free(mdata);
> +	return ret;
> +}
> +
> +u8 fwu_update_checks_pass(void)
> +{
> +	return !trial_state && boottime_check;
> +}
> +
> +int fwu_boottime_checks(void)
> +{
> +	int ret;
> +	u32 boot_idx, active_idx;
> +
> +	ret = fwu_mdata_check();
> +	if (ret < 0) {
> +		boottime_check = 0;
> +		return 0;
> +	}
> +
> +	/*
> +	 * Get the Boot Index, i.e. the bank from
> +	 * which the platform has booted. This value
> +	 * gets passed from the ealier stage bootloader
> +	 * which booted u-boot, e.g. tf-a. If the
> +	 * boot index is not the same as the
> +	 * active_index read from the FWU metadata,
> +	 * update the active_index.
> +	 */
> +	fwu_plat_get_bootidx(&boot_idx);
> +	if (boot_idx >= CONFIG_FWU_NUM_BANKS) {
> +		log_err("Received incorrect value of boot_index\n");
> +		boottime_check = 0;
> +		return 0;
> +	}
> +
> +	ret = fwu_get_active_index(&active_idx);
> +	if (ret < 0) {
> +		log_err("Unable to read active_index\n");
> +		boottime_check = 0;
> +		return 0;
> +	}
> +
> +	if (boot_idx != active_idx) {
> +		log_info("Boot idx %u is not matching active idx %u, changing active_idx\n",
> +			 boot_idx, active_idx);
> +		ret = fwu_update_active_index(boot_idx);
> +		if (ret < 0)
> +			boottime_check = 0;
> +		else
> +			boottime_check = 1;
> +
> +		return 0;
> +	}
> +
> +	ret = fwu_trial_state_check();
> +	if (ret < 0)
> +		boottime_check = 0;
> +	else
> +		boottime_check = 1;
> +
> +	return 0;
> +}
> -- 
> 2.17.1
>