block: sed-opal: Change the check condition for regular session validity

This patch changes the check condition for the validity/authentication
of the session.

1. The Host Session Number(HSN) in the response should match the HSN for
   the session.
2. The TPER Session Number(TSN) can never be less than 4096 for a regular
   session.

Reference:
Section 3.2.2.1   of https://trustedcomputinggroup.org/wp-content/uploads/TCG_Storage_Opal_SSC_Application_Note_1-00_1-00-Final.pdf
Section 3.3.7.1.1 of https://trustedcomputinggroup.org/wp-content/uploads/TCG_Storage_Architecture_Core_Spec_v2.01_r1.00.pdfCo-developed-by: Andrzej Jakowski <andrzej.jakowski@linux.intel.com>
Signed-off-by: Andrzej Jakowski <andrzej.jakowski@linux.intel.com>
Signed-off-by: Revanth Rajashekar <revanth.rajashekar@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/opal_proto.h

@@ -36,6 +36,7 @@ enum opal_response_token {
 
 #define DTAERROR_NO_METHOD_STATUS 0x89
 #define GENERIC_HOST_SESSION_NUM 0x41
+#define FIRST_TPER_SESSION_NUM	4096
 
 #define TPER_SYNC_SUPPORTED 0x01
 #define MBR_ENABLED_MASK 0x10

block/sed-opal.c

@@ -1056,7 +1056,7 @@ static int start_opal_session_cont(struct opal_dev *dev)
 	hsn = response_get_u64(&dev->parsed, 4);
 	tsn = response_get_u64(&dev->parsed, 5);
 
-	if (hsn == 0 && tsn == 0) {
+	if (hsn != GENERIC_HOST_SESSION_NUM || tsn < FIRST_TPER_SESSION_NUM) {
 		pr_debug("Couldn't authenticate session\n");
 		return -EPERM;
 	}