target: Fail I/O with PROTECT bit when protection is unsupported

This patch adds an explicit check for WRPROTECT + RDPROTECT bit usage
within sbc_check_prot(), and fails with TCM_INVALID_CDB_FIELD if the
backend device does not have protection enabled.

Also, update sbc_check_prot() to return sense_reason_t in order to
propigate up the correct sense ASQ.

Cc: Martin Petersen <martin.petersen@oracle.com>
Cc: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_sbc.c

@@ -626,14 +626,21 @@ sbc_set_prot_op_checks(u8 protect, enum target_prot_type prot_type,
 	return 0;
 }
 
-static bool
+static sense_reason_t
 sbc_check_prot(struct se_device *dev, struct se_cmd *cmd, unsigned char *cdb,
 	       u32 sectors, bool is_write)
 {
 	u8 protect = cdb[1] >> 5;
 
-	if ((!cmd->t_prot_sg || !cmd->t_prot_nents) && cmd->prot_pto)
-		return true;
+	if (!cmd->t_prot_sg || !cmd->t_prot_nents) {
+		if (protect && !dev->dev_attrib.pi_prot_type) {
+			pr_err("CDB contains protect bit, but device does not"
+			       " advertise PROTECT=1 feature bit\n");
+			return TCM_INVALID_CDB_FIELD;
+		}
+		if (cmd->prot_pto)
+			return TCM_NO_SENSE;
+	}
 
 	switch (dev->dev_attrib.pi_prot_type) {
 	case TARGET_DIF_TYPE3_PROT:
@@ -641,7 +648,7 @@ sbc_check_prot(struct se_device *dev, struct se_cmd *cmd, unsigned char *cdb,
 		break;
 	case TARGET_DIF_TYPE2_PROT:
 		if (protect)
-			return false;
+			return TCM_INVALID_CDB_FIELD;
 
 		cmd->reftag_seed = cmd->t_task_lba;
 		break;
@@ -650,12 +657,12 @@ sbc_check_prot(struct se_device *dev, struct se_cmd *cmd, unsigned char *cdb,
 		break;
 	case TARGET_DIF_TYPE0_PROT:
 	default:
-		return true;
+		return TCM_NO_SENSE;
 	}
 
 	if (sbc_set_prot_op_checks(protect, dev->dev_attrib.pi_prot_type,
 				   is_write, cmd))
-		return false;
+		return TCM_INVALID_CDB_FIELD;
 
 	cmd->prot_type = dev->dev_attrib.pi_prot_type;
 	cmd->prot_length = dev->prot_length * sectors;
@@ -674,7 +681,7 @@ sbc_check_prot(struct se_device *dev, struct se_cmd *cmd, unsigned char *cdb,
 		 __func__, cmd->prot_type, cmd->data_length, cmd->prot_length,
 		 cmd->prot_op, cmd->prot_checks);
 
-	return true;
+	return TCM_NO_SENSE;
 }
 
 sense_reason_t
@@ -698,8 +705,9 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 		sectors = transport_get_sectors_10(cdb);
 		cmd->t_task_lba = transport_lba_32(cdb);
 
-		if (!sbc_check_prot(dev, cmd, cdb, sectors, false))
-			return TCM_UNSUPPORTED_SCSI_OPCODE;
+		ret = sbc_check_prot(dev, cmd, cdb, sectors, false);
+		if (ret)
+			return ret;
 
 		cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
 		cmd->execute_rw = ops->execute_rw;
@@ -709,8 +717,9 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 		sectors = transport_get_sectors_12(cdb);
 		cmd->t_task_lba = transport_lba_32(cdb);
 
-		if (!sbc_check_prot(dev, cmd, cdb, sectors, false))
-			return TCM_UNSUPPORTED_SCSI_OPCODE;
+		ret = sbc_check_prot(dev, cmd, cdb, sectors, false);
+		if (ret)
+			return ret;
 
 		cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
 		cmd->execute_rw = ops->execute_rw;
@@ -720,8 +729,9 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 		sectors = transport_get_sectors_16(cdb);
 		cmd->t_task_lba = transport_lba_64(cdb);
 
-		if (!sbc_check_prot(dev, cmd, cdb, sectors, false))
-			return TCM_UNSUPPORTED_SCSI_OPCODE;
+		ret = sbc_check_prot(dev, cmd, cdb, sectors, false);
+		if (ret)
+			return ret;
 
 		cmd->se_cmd_flags |= SCF_SCSI_DATA_CDB;
 		cmd->execute_rw = ops->execute_rw;
@@ -739,8 +749,9 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 		sectors = transport_get_sectors_10(cdb);
 		cmd->t_task_lba = transport_lba_32(cdb);
 
-		if (!sbc_check_prot(dev, cmd, cdb, sectors, true))
-			return TCM_UNSUPPORTED_SCSI_OPCODE;
+		ret = sbc_check_prot(dev, cmd, cdb, sectors, true);
+		if (ret)
+			return ret;
 
 		if (cdb[1] & 0x8)
 			cmd->se_cmd_flags |= SCF_FUA;
@@ -752,8 +763,9 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 		sectors = transport_get_sectors_12(cdb);
 		cmd->t_task_lba = transport_lba_32(cdb);
 
-		if (!sbc_check_prot(dev, cmd, cdb, sectors, true))
-			return TCM_UNSUPPORTED_SCSI_OPCODE;
+		ret = sbc_check_prot(dev, cmd, cdb, sectors, true);
+		if (ret)
+			return ret;
 
 		if (cdb[1] & 0x8)
 			cmd->se_cmd_flags |= SCF_FUA;
@@ -765,8 +777,9 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
 		sectors = transport_get_sectors_16(cdb);
 		cmd->t_task_lba = transport_lba_64(cdb);
 
-		if (!sbc_check_prot(dev, cmd, cdb, sectors, true))
-			return TCM_UNSUPPORTED_SCSI_OPCODE;
+		ret = sbc_check_prot(dev, cmd, cdb, sectors, true);
+		if (ret)
+			return ret;
 
 		if (cdb[1] & 0x8)
 			cmd->se_cmd_flags |= SCF_FUA;