g: update: expose USB PDU verification function

Some upcoming changes will introduce transfer of vendor and extension
commands over the usb updater endpoint.

This patch exposes a function which allows to verify integrity of
received USB PDUs.

BRANCH=none
BUG=chrome-os-partner:60013
TEST=no functional changes, usb_updater still works fine.

Change-Id: I8d9e6746ef0dfbb17bba618410514ca047a59a45
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/414441
Reviewed-by: Mary Ruthven <mruthven@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/439091
Reviewed-by: Youcheng Syu <youcheng@google.com>
Commit-Queue: Youcheng Syu <youcheng@google.com>
Tested-by: Youcheng Syu <youcheng@google.com>

2 files changed, 26 insertions, 12 deletions

diff --git a/chip/g/upgrade_fw.c b/chip/g/upgrade_fw.c
index 0eed2c51a4..f77d4145e8 100644
--- a/chip/g/upgrade_fw.c
+++ b/chip/g/upgrade_fw.c
@@ -148,6 +148,27 @@ static uint8_t check_update_chunk(uint32_t block_offset, size_t body_size)
 	return UPGRADE_BAD_ADDR;
 }
 
+int usb_pdu_valid(struct upgrade_command *cmd_body,  size_t cmd_size)
+{
+	uint8_t sha1_digest[SHA_DIGEST_SIZE];
+	size_t body_size = cmd_size - offsetof(struct update_frame_header,
+					       cmd.block_base);
+
+	/* Check if the block was received properly. */
+	DCRYPTO_SHA1_hash((uint8_t *)&cmd_body->block_base,
+			  body_size + sizeof(cmd_body->block_base),
+			  sha1_digest);
+	if (memcmp(sha1_digest, &cmd_body->block_digest,
+		   sizeof(cmd_body->block_digest))) {
+		CPRINTF("%s:%d sha1 %x not equal received %x\n",
+			__func__, __LINE__,
+			*(uint32_t *)sha1_digest, cmd_body->block_digest);
+		return 0;
+	}
+
+	return 1;
+}
+
 void fw_upgrade_command_handler(void *body,
 				size_t cmd_size,
 				size_t *response_size)
@@ -155,7 +176,6 @@ void fw_upgrade_command_handler(void *body,
 	struct upgrade_command *cmd_body = body;
 	void *upgrade_data;
 	uint8_t *error_code = body;  /* Cache the address for code clarity. */
-	uint8_t sha1_digest[SHA_DIGEST_SIZE];
 	size_t body_size;
 	uint32_t block_offset;
 
@@ -224,20 +244,10 @@ void fw_upgrade_command_handler(void *body,
 		return;
 	}
 
-	/* Check if the block was received properly. */
-	DCRYPTO_SHA1_hash((uint8_t *)&cmd_body->block_base,
-			  body_size + sizeof(cmd_body->block_base),
-			  sha1_digest);
-
 	block_offset = be32toh(cmd_body->block_base);
 
-	if (memcmp(sha1_digest, &cmd_body->block_digest,
-		   sizeof(cmd_body->block_digest))) {
+	if (!usb_pdu_valid(cmd_body, cmd_size)) {
 		*error_code = UPGRADE_DATA_ERROR;
-		CPRINTF("%s:%d sha1 %x not equal received %x at offs. 0x%x\n",
-			__func__, __LINE__,
-			*(uint32_t *)sha1_digest, cmd_body->block_digest,
-			block_offset);
 		return;
 	}
 
diff --git a/chip/g/upgrade_fw.h b/chip/g/upgrade_fw.h
index cab1f083ca..01e8addbc4 100644
--- a/chip/g/upgrade_fw.h
+++ b/chip/g/upgrade_fw.h
@@ -122,6 +122,10 @@ void fw_upgrade_command_handler(void *body,
 /* Used to tell fw upgrade the update ran successfully and is finished */
 void fw_upgrade_complete(void);
 
+/* Verify integrity of the PDU received over USB. */
+int usb_pdu_valid(struct upgrade_command *cmd_body,
+		  size_t cmd_size);
+
 /* Various upgrade command return values. */
 enum return_value {
 	UPGRADE_SUCCESS = 0,