[iot] Support authenticated unlock

Add fastboot commands "fastboot oem at-get-vboot-unlock-challenge"
and "fastboot oem at-unlock-vboot" to support the authenticated
unlock feature for Android Things devices. Use software random
numbers generator to generate the 16 bytes random challenge, it
should be replaced with hardware encrypted random generator when
the TEE part is ready.

Test: Generate unlock challenge by:
        ./avbtool make_atx_unlock_credential
        --output=atx_unlock_credential.bin
        --intermediate_key_certificate=atx_pik_certificate.bin
        --unlock_key_certificate=atx_puk_certificate.bin
        --challenge=my_generated_challenge.bin
        --unlock_key=testkey_atx_puk.pem
      validated the unlock credential successfully on imx7d_pico
      and AIY.

Change-Id: I4b8cee87c9e96924169479b65020a081136681f6
Signed-off-by: Ji Luo <ji.luo@nxp.com>

1 files changed, 35 insertions, 4 deletions

diff --git a/drivers/usb/gadget/f_fastboot.c b/drivers/usb/gadget/f_fastboot.c
index eefd54b6ac..0a185156f1 100644
--- a/drivers/usb/gadget/f_fastboot.c
+++ b/drivers/usb/gadget/f_fastboot.c
@@ -1640,10 +1640,11 @@ static AvbAtxOps fsl_avb_atx_ops = {
 	.read_permanent_attributes = fsl_read_permanent_attributes,
 	.read_permanent_attributes_hash = fsl_read_permanent_attributes_hash,
 #ifdef CONFIG_IMX_TRUSTY_OS
-	.set_key_version = fsl_write_rollback_index_rpmb
+	.set_key_version = fsl_write_rollback_index_rpmb,
 #else
-	.set_key_version = fsl_set_key_version
+	.set_key_version = fsl_set_key_version,
 #endif
+	.get_random = fsl_get_random
 };
 #endif
 static AvbOps fsl_avb_ops = {
@@ -3320,6 +3321,27 @@ static void cb_flashing(struct usb_ep *ep, struct usb_request *req)
 			strcpy(response, "FAILInternal error!");
 		else
 			strcpy(response, "OKAY");
+	} else if (endswith(cmd, FASTBOOT_AT_GET_UNLOCK_CHALLENGE)) {
+		if (avb_atx_get_unlock_challenge(fsl_avb_ops.atx_ops,
+						interface.transfer_buffer, &download_bytes))
+			strcpy(response, "FAILInternal error!");
+		else
+			strcpy(response, "OKAY");
+	} else if (endswith(cmd, FASTBOOT_AT_UNLOCK_VBOOT)) {
+#ifdef CONFIG_AT_AUTHENTICATE_UNLOCK
+		if (avb_atx_verify_unlock_credential(fsl_avb_ops.atx_ops,
+							interface.transfer_buffer))
+			strcpy(response, "FAILIncorrect unlock credential!");
+		else {
+#endif
+			status = do_fastboot_unlock(true);
+			if (status != FASTBOOT_LOCK_ERROR)
+				strcpy(response, "OKAY");
+			else
+				strcpy(response, "FAILunlock device failed.");
+#ifdef CONFIG_AT_AUTHENTICATE_UNLOCK
+		}
+#endif
 	}
 #endif /* CONFIG_AVB_ATX */
 #ifdef CONFIG_ANDROID_THINGS_SUPPORT
@@ -3366,11 +3388,18 @@ static void cb_flashing(struct usb_ep *ep, struct usb_request *req)
 		strcpy(response, "OKAY");
 	} else if (endswith(cmd, "unlock")) {
 		printf("flashing unlock.\n");
+#ifdef CONFIG_AVB_ATX
+		/* We should do nothing here For Android Things which
+		 * enables the authenticated unlock feature.
+		 */
+		strcpy(response, "OKAY");
+#else
 		status = do_fastboot_unlock(false);
 		if (status != FASTBOOT_LOCK_ERROR)
 			strcpy(response, "OKAY");
 		else
 			strcpy(response, "FAILunlock device failed.");
+#endif
 	} else if (endswith(cmd, "lock")) {
 		printf("flashing lock.\n");
 		status = do_fastboot_lock();
@@ -3438,7 +3467,8 @@ static void cb_flash(struct usb_ep *ep, struct usb_request *req)
 	/* initialize the response buffer */
 	fb_response_str = response;
 
-#ifdef CONFIG_FASTBOOT_LOCK
+	/* Always enable image flash for Android Things. */
+#if defined(CONFIG_FASTBOOT_LOCK) && !defined(CONFIG_AVB_ATX)
 	/* for imx8 boot from USB, lock status can be ignored for uuu.*/
 	if (!(is_imx8() || is_imx8m()) || !(is_boot_from_usb())) {
 		int status;
@@ -3462,6 +3492,7 @@ static void cb_flash(struct usb_ep *ep, struct usb_request *req)
 	fastboot_fail("no flash device defined");
 
 	rx_process_flash(cmd);
+
 #ifdef CONFIG_FASTBOOT_LOCK
 	if (strncmp(cmd, "gpt", 3) == 0) {
 		int gpt_valid = 0;
@@ -3497,7 +3528,7 @@ static void cb_erase(struct usb_ep *ep, struct usb_request *req)
 	/* initialize the response buffer */
 	fb_response_str = response;
 
-#ifdef CONFIG_FASTBOOT_LOCK
+#if defined(CONFIG_FASTBOOT_LOCK) && !defined(CONFIG_AVB_ATX)
 	FbLockState status;
 	status = fastboot_get_lock_stat();
 	if (status == FASTBOOT_LOCK) {