On Thu 23 Jan 2025 at 14:38, Mattijs Korpershoek mkorpershoek@baylibre.com wrote:

When booting an Android build with AVB enabled, it's still possible to deactivate the check for development purposes if the bootloader state is UNLOCKED.

This is very useful for development and can be done at flashing time via: $ fastboot flash --disable-verity --disable-verification vbmeta vbmeta.img

However, with bootmeth_android, we cannot boot this way:

Scanning bootdev 'mmc@fa10000.bootdev':
  0  android      ready   mmc          0  mmc@fa10000.bootdev.whole
** Booting bootflow 'mmc@fa10000.bootdev.whole' with android
avb_vbmeta_image.c:188: ERROR: Hash does not match!
avb_slot_verify.c:732: ERROR: vbmeta_a: Error verifying vbmeta image: HASH_MISMATCH
get_partition: can't find partition '_a'
avb_slot_verify.c:496: ERROR: _a: Error determining partition size.
Verification failed, reason: I/O error occurred while trying to load data
Boot failed (err=-5)
No more bootdevs

From the logs we can see that avb tries to read a partition named '_a'. It's doing so because the last element of requested_partitions implicitly is '\0', but the doc explicitly request it to be NULL instead.

Add NULL as last element to requested_partitions to avoid this problem.

Fixes: 125d9f3306ea ("bootstd: Add a bootmeth for Android") Signed-off-by: Mattijs Korpershoek mkorpershoek@baylibre.com

---

boot/bootmeth_android.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/boot/bootmeth_android.c b/boot/bootmeth_android.c index 19b1f2c377b9a51ff1683259085e1d636c939413..2cd167f80280801618a317a65e93a10e70a0d9ee 100644 --- a/boot/bootmeth_android.c +++ b/boot/bootmeth_android.c @@ -380,7 +380,7 @@ static int run_avb_verification(struct bootflow *bflow) { struct blk_desc *desc = dev_get_uclass_plat(bflow->blk); struct android_priv *priv = bflow->bootmeth_priv;

• const char * const requested_partitions[] = {"boot", "vendor_boot"};

• const char * const requested_partitions[] = {"boot", "vendor_boot", NULL}; struct AvbOps *avb_ops; AvbSlotVerifyResult result; AvbSlotVerifyData *out_data;

-- 2.47.1

Reviewed-by: Julien Masson jmasson@baylibre.com

On Thu 23 Jan 2025 at 14:40, Mattijs Korpershoek mkorpershoek@baylibre.com wrote:

When the bootloader is UNLOCKED, it should be possible to boot Android even if AVB reports verification errors [1].

This allows developers to flash modified partitions on userdebug/engineering builds.

Developers can do so on unlocked devices with: $ fastboot flash --disable-verity --disable-verification vbmeta vbmeta.img

In such case, bootmeth_android refuses to boot.

Allow the boot to continue when the device is UNLOCKED and AVB reports verification errors.

[1] https://source.android.com/docs/security/features/verifiedboot/boot-flow#unl... Fixes: 125d9f3306ea ("bootstd: Add a bootmeth for Android") Signed-off-by: Mattijs Korpershoek mkorpershoek@baylibre.com

---

boot/bootmeth_android.c | 37 ++++++++++++++++++++++++------------- 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/boot/bootmeth_android.c b/boot/bootmeth_android.c index 2cd167f80280801618a317a65e93a10e70a0d9ee..dc9aad1633bb7a6d577013bfa0f939343f2e066b 100644 --- a/boot/bootmeth_android.c +++ b/boot/bootmeth_android.c @@ -407,17 +407,26 @@ static int run_avb_verification(struct bootflow *bflow) AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE, &out_data);

• if (result != AVB_SLOT_VERIFY_RESULT_OK) {

• printf("Verification failed, reason: %s\n",
  

•        str_avb_slot_error(result));
  

• avb_slot_verify_data_free(out_data);
  

• return log_msg_ret("avb verify", -EIO);
  

• }
• if (unlocked)

• boot_state = AVB_ORANGE;
  

• else

• if (!unlocked) {

• /* When device is locked, we only accept AVB_SLOT_VERIFY_RESULT_OK */
  

• if (result != AVB_SLOT_VERIFY_RESULT_OK) {
  

• 	printf("Verification failed, reason: %s\n",
  

• 	       str_avb_slot_error(result));
  

• 	avb_slot_verify_data_free(out_data);
  

• 	return log_msg_ret("avb verify", -EIO);
  

• }
  

  boot_state = AVB_GREEN;

• } else {

• /* When device is unlocked, we also accept verification errors */
  

• if (result != AVB_SLOT_VERIFY_RESULT_OK &&
  

•     result != AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION) {
  

• 	printf("Unlocked verification failed, reason: %s\n",
  

• 	       str_avb_slot_error(result));
  

• 	avb_slot_verify_data_free(out_data);
  

• 	return log_msg_ret("avb verify unlocked", -EIO);
  

• }
  

• boot_state = AVB_ORANGE;
  

• }

  extra_args = avb_set_state(avb_ops, boot_state); if (extra_args) {

@@ -427,9 +436,11 @@ static int run_avb_verification(struct bootflow *bflow) goto free_out_data; }

• ret = avb_append_commandline(bflow, out_data->cmdline);
• if (ret < 0)

• goto free_out_data;
  

• if (result == AVB_SLOT_VERIFY_RESULT_OK) {

• ret = avb_append_commandline(bflow, out_data->cmdline);
  

• if (ret < 0)
  

• 	goto free_out_data;
  

• }

  return 0;

-- 2.47.1

Reviewed-by: Julien Masson jmasson@baylibre.com