[PATCH 2/2] bootstd: android: Allow boot with AVB failures when unlocked

[Mattijs Korpershoek]

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#unlocked-devices
Fixes: 125d9f3306ea ("bootstd: Add a bootmeth for Android")
Signed-off-by: Mattijs Korpershoek <mkorpershoek at baylibre.com>
---
 boot/bootmeth_android.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/boot/bootmeth_android.c b/boot/bootmeth_android.c
index 2cd167f80280801618a317a65e93a10e70a0d9ee..564d21784feb0667bf9bed2a59be0a232601a7dd 100644
--- a/boot/bootmeth_android.c
+++ b/boot/bootmeth_android.c
@@ -407,11 +407,16 @@ static int run_avb_verification(struct bootflow *bflow)
 				 AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE,
 				 &out_data);
 
-	if (result != AVB_SLOT_VERIFY_RESULT_OK) {
+	if (result != AVB_SLOT_VERIFY_RESULT_OK && !unlocked) {
 		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);
+	} else if (result != AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION && unlocked) {
+		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);
 	}
 
 	if (unlocked)
@@ -427,9 +432,11 @@ 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