[PATCH v13 09/15] FWU: Add boot time checks as highlighted by the FWU specification

Sughosh Ganu
2022-10-06T09:08:52Z

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.

Call these checks through the main loop event at the time of platform
boot.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Etienne Carriere <etienne.carriere@linaro.org>
---
Changes since V12: None

include/fwu.h | 13 +++
lib/fwu_updates/fwu.c | 191 +++++++++++++++++++++++++++++++++++++++++-
2 files changed, 203 insertions(+), 1 deletion(-)

diff --git a/include/fwu.h b/include/fwu.h
index 71a03cf70b..2effa7da38 100644
--- a/include/fwu.h
+++ b/include/fwu.h
@@ -253,4 +253,17 @@ int fwu_plat_get_update_index(uint *update_idx);
*
*/
void fwu_plat_get_bootidx(uint *boot_idx);
+
+/**
+ * fwu_update_checks_pass() - Check if FWU update can be done
+ *
+ * Check if the FWU update can be executed. The updates are
+ * allowed only when the platform is not in Trial State and
+ * the boot time checks have passed
+ *
+ * Return: 1 if OK, 0 on error
+ *
+ */
+u8 fwu_update_checks_pass(void);
+
#endif /* _FWU_H_ */
diff --git a/lib/fwu_updates/fwu.c b/lib/fwu_updates/fwu.c
index 70482d14a0..b14c0dfadd 100644
--- a/lib/fwu_updates/fwu.c
+++ b/lib/fwu_updates/fwu.c
@@ -4,10 +4,19 @@
*/

#include <dm.h>
+#include <efi.h>
#include <efi_loader.h>
+#include <efi_variable.h>
+#include <event.h>
#include <fwu.h>
#include <fwu_mdata.h>
-#include <log.h>
+#include <malloc.h>
+
+#include <linux/errno.h>
+#include <linux/types.h>
+
+static u8 trial_state;
+static u8 boottime_check;

#include <linux/errno.h>
#include <linux/types.h>
@@ -18,6 +27,112 @@ enum {
IMAGE_ACCEPT_CLEAR,
};

+static int trial_counter_update(u16 *trial_state_ctr)
+{
+ bool delete;
+ u32 var_attr;
+ efi_status_t status;
+ efi_uintn_t var_size;
+
+ delete = !trial_state_ctr ? true : false;
+ var_size = !trial_state_ctr ? 0 : (efi_uintn_t)sizeof(*trial_state_ctr);
+ var_attr = !trial_state_ctr ? 0 : EFI_VARIABLE_NON_VOLATILE |
+ EFI_VARIABLE_BOOTSERVICE_ACCESS;
+ status = efi_set_variable_int(u"TrialStateCtr",
+ &efi_global_variable_guid,
+ var_attr,
+ var_size, trial_state_ctr, false);
+
+ if ((delete && (status != EFI_NOT_FOUND &&
+ status != EFI_SUCCESS)) ||
+ (!delete && status != EFI_SUCCESS))
+ return -1;
+
+ return 0;
+}
+
+static int in_trial_state(struct fwu_mdata *mdata)
+{
+ u32 i, active_bank;
+ struct fwu_image_entry *img_entry;
+ struct fwu_image_bank_info *img_bank_info;
+
+ active_bank = mdata->active_index;
+ img_entry = &mdata->img_entry[0];
+ for (i = 0; i < CONFIG_FWU_NUM_IMAGES_PER_BANK; i++) {
+ img_bank_info = &img_entry[i].img_bank_info[active_bank];
+ if (!img_bank_info->accepted) {
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+static int fwu_trial_state_check(struct udevice *dev)
+{
+ int ret;
+ efi_status_t status;
+ efi_uintn_t var_size;
+ u16 trial_state_ctr;
+ u32 var_attributes;
+ struct fwu_mdata mdata = { 0 };
+
+ ret = fwu_get_mdata(dev, &mdata);
+ if (ret)
+ return ret;
+
+ trial_state = in_trial_state(&mdata);
+ 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;
+ status = efi_get_variable_int(u"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");
+ ret = fwu_revert_boot_index();
+ if (ret) {
+ log_err("Unable to revert active_index\n");
+ goto out;
+ }
+
+ /* Delete the TrialStateCtr variable */
+ ret = trial_counter_update(NULL);
+ if (ret) {
+ log_err("Unable to delete TrialStateCtr variable\n");
+ goto out;
+ }
+ } else {
+ ret = trial_counter_update(&trial_state_ctr);
+ if (ret) {
+ log_err("Unable to increment TrialStateCtr variable\n");
+ goto out;
+ }
+ }
+ } else {
+ /* Delete the variable */
+ ret = trial_counter_update(NULL);
+ if (ret) {
+ log_err("Unable to delete TrialStateCtr variable\n");
+ }
+ }
+
+out:
+ return ret;
+}
+
static int fwu_get_dev_mdata(struct udevice **dev, struct fwu_mdata *mdata)
{
int ret;
@@ -28,6 +143,9 @@ static int fwu_get_dev_mdata(struct udevice **dev, struct fwu_mdata *mdata)
return ret;
}

+ if (!mdata)
+ return 0;
+
ret = fwu_get_mdata(*dev, mdata);
if (ret < 0)
log_debug("Unable to get valid FWU metadata\n");
@@ -389,3 +507,74 @@ __weak int fwu_plat_get_update_index(uint *update_idx)

return ret;
}
+
+/**
+ * fwu_update_checks_pass() - Check if FWU update can be done
+ *
+ * Check if the FWU update can be executed. The updates are
+ * allowed only when the platform is not in Trial State and
+ * the boot time checks have passed
+ *
+ * Return: 1 if OK, 0 on error
+ *
+ */
+u8 fwu_update_checks_pass(void)
+{
+ return !trial_state && boottime_check;
+}
+
+static int fwu_boottime_checks(void *ctx, struct event *event)
+{
+ int ret;
+ struct udevice *dev;
+ u32 boot_idx, active_idx;
+
+ ret = fwu_get_dev_mdata(&dev, NULL);
+ if (ret)
+ return ret;
+
+ ret = fwu_mdata_check(dev);
+ if (ret)
+ 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");
+ return 0;
+ }
+
+ ret = fwu_get_active_index(&active_idx);
+ if (ret) {
+ log_err("Unable to read active_index\n");
+ 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_set_active_index(boot_idx);
+ if (!ret)
+ boottime_check = 1;
+
+ return 0;
+ }
+
+ if (efi_init_obj_list() != EFI_SUCCESS)
+ return 0;
+
+ ret = fwu_trial_state_check(dev);
+ if (!ret)
+ boottime_check = 1;
+
+ return 0;
+}
+EVENT_SPY(EVT_MAIN_LOOP, fwu_boottime_checks);
--
2.34.1