iscsi-target: Add login_keys_workaround attribute for non RFC initiators

This patch re-introduces part of a long standing login workaround that
was recently dropped by:

commit 1c99de981f30b3e7868b8d20ce5479fa1c0fea46
Author: Nicholas Bellinger <[e-mail]>
Date: Sun Apr 2 13:36:44 2017 -0700

iscsi-target: Drop work-around for legacy GlobalSAN initiator

Namely, the workaround for FirstBurstLength ended up being required by
Mellanox Flexboot PXE boot ROMs as reported by Robert.

So this patch re-adds the work-around for FirstBurstLength within
iscsi_check_proposer_for_optional_reply(), and makes the key optional
to respond when the initiator does not propose, nor respond to it.

Also as requested by Arun, this patch introduces a new TPG attribute
named 'login_keys_workaround' that controls the use of both the
FirstBurstLength workaround, as well as the two other existing
workarounds for gPXE iSCSI boot client.

By default, the workaround is enabled with login_keys_workaround=1,
since Mellanox FlexBoot requires it, and Arun has verified the Qlogic
MSFT initiator already proposes FirstBurstLength, so it's uneffected
by this re-adding this part of the original work-around.

Reported-by: Robert LeBlanc <[e-mail]>
Cc: Robert LeBlanc <[e-mail]>
Reviewed-by: Arun Easi <[e-mail]>
Cc: <[e-mail]> # 3.1+
Signed-off-by: Nicholas Bellinger <[e-mail]>

drivers/target/iscsi/iscsi_target_configfs.c

···
 DEF_TPG_ATTRIB(t10_pi);
 DEF_TPG_ATTRIB(fabric_prot_type);
 DEF_TPG_ATTRIB(tpg_enabled_sendtargets);
+DEF_TPG_ATTRIB(login_keys_workaround);
 
 static struct configfs_attribute *lio_target_tpg_attrib_attrs[] = {
 	&iscsi_tpg_attrib_attr_authentication,
···
 	&iscsi_tpg_attrib_attr_t10_pi,
 	&iscsi_tpg_attrib_attr_fabric_prot_type,
 	&iscsi_tpg_attrib_attr_tpg_enabled_sendtargets,
+	&iscsi_tpg_attrib_attr_login_keys_workaround,
 	NULL,
 };
 

drivers/target/iscsi/iscsi_target_nego.c

···
 			SENDER_TARGET,
 			login->rsp_buf,
 			&login->rsp_length,
-			conn->param_list);
+			conn->param_list,
+			conn->tpg->tpg_attrib.login_keys_workaround);
 	if (ret < 0)
 		return -1;
 
···
 			SENDER_TARGET,
 			login->rsp_buf,
 			&login->rsp_length,
-			conn->param_list);
+			conn->param_list,
+			conn->tpg->tpg_attrib.login_keys_workaround);
 	if (ret < 0) {
 		iscsit_tx_login_rsp(conn, ISCSI_STATUS_CLS_INITIATOR_ERR,
 				ISCSI_LOGIN_STATUS_INIT_ERR);

drivers/target/iscsi/iscsi_target_parameters.c

···
 	return 0;
 }
 
-static void iscsi_check_proposer_for_optional_reply(struct iscsi_param *param)
+static void iscsi_check_proposer_for_optional_reply(struct iscsi_param *param,
+						    bool keys_workaround)
 {
 	if (IS_TYPE_BOOL_AND(param)) {
 		if (!strcmp(param->value, NO))
···
 	} else if (IS_TYPE_BOOL_OR(param)) {
 		if (!strcmp(param->value, YES))
 			SET_PSTATE_REPLY_OPTIONAL(param);
-		 /*
-		  * Required for gPXE iSCSI boot client
-		  */
-		if (!strcmp(param->name, IMMEDIATEDATA))
-			SET_PSTATE_REPLY_OPTIONAL(param);
+
+		if (keys_workaround) {
+			/*
+			 * Required for gPXE iSCSI boot client
+			 */
+			if (!strcmp(param->name, IMMEDIATEDATA))
+				SET_PSTATE_REPLY_OPTIONAL(param);
+		}
 	} else if (IS_TYPE_NUMBER(param)) {
 		if (!strcmp(param->name, MAXRECVDATASEGMENTLENGTH))
 			SET_PSTATE_REPLY_OPTIONAL(param);
-		/*
-		 * Required for gPXE iSCSI boot client
-		 */
-		if (!strcmp(param->name, MAXCONNECTIONS))
-			SET_PSTATE_REPLY_OPTIONAL(param);
+
+		if (keys_workaround) {
+			/*
+			 * Required for Mellanox Flexboot PXE boot ROM
+			 */
+			if (!strcmp(param->name, FIRSTBURSTLENGTH))
+				SET_PSTATE_REPLY_OPTIONAL(param);
+
+			/*
+			 * Required for gPXE iSCSI boot client
+			 */
+			if (!strcmp(param->name, MAXCONNECTIONS))
+				SET_PSTATE_REPLY_OPTIONAL(param);
+		}
 	} else if (IS_PHASE_DECLARATIVE(param))
 		SET_PSTATE_REPLY_OPTIONAL(param);
 }
···
 	u8 sender,
 	char *textbuf,
 	u32 *length,
-	struct iscsi_param_list *param_list)
+	struct iscsi_param_list *param_list,
+	bool keys_workaround)
 {
 	char *output_buf = NULL;
 	struct iscsi_extra_response *er;
···
 			*length += 1;
 			output_buf = textbuf + *length;
 			SET_PSTATE_PROPOSER(param);
-			iscsi_check_proposer_for_optional_reply(param);
+			iscsi_check_proposer_for_optional_reply(param,
+							        keys_workaround);
 			pr_debug("Sending key: %s=%s\n",
 				param->name, param->value);
 		}

drivers/target/iscsi/iscsi_target_parameters.h

···
 extern int iscsi_update_param_value(struct iscsi_param *, char *);
 extern int iscsi_decode_text_input(u8, u8, char *, u32, struct iscsi_conn *);
 extern int iscsi_encode_text_output(u8, u8, char *, u32 *,
-			struct iscsi_param_list *);
+			struct iscsi_param_list *, bool);
 extern int iscsi_check_negotiated_keys(struct iscsi_param_list *);
 extern void iscsi_set_connection_parameters(struct iscsi_conn_ops *,
 			struct iscsi_param_list *);

drivers/target/iscsi/iscsi_target_tpg.c

···
 	a->t10_pi = TA_DEFAULT_T10_PI;
 	a->fabric_prot_type = TA_DEFAULT_FABRIC_PROT_TYPE;
 	a->tpg_enabled_sendtargets = TA_DEFAULT_TPG_ENABLED_SENDTARGETS;
+	a->login_keys_workaround = TA_DEFAULT_LOGIN_KEYS_WORKAROUND;
 }
 
 int iscsit_tpg_add_portal_group(struct iscsi_tiqn *tiqn, struct iscsi_portal_group *tpg)
···
 	a->tpg_enabled_sendtargets = flag;
 	pr_debug("iSCSI_TPG[%hu] - TPG enabled bit required for SendTargets:"
 		" %s\n", tpg->tpgt, (a->tpg_enabled_sendtargets) ? "ON" : "OFF");
+
+	return 0;
+}
+
+int iscsit_ta_login_keys_workaround(
+	struct iscsi_portal_group *tpg,
+	u32 flag)
+{
+	struct iscsi_tpg_attrib *a = &tpg->tpg_attrib;
+
+	if ((flag != 0) && (flag != 1)) {
+		pr_err("Illegal value %d\n", flag);
+		return -EINVAL;
+	}
+
+	a->login_keys_workaround = flag;
+	pr_debug("iSCSI_TPG[%hu] - TPG enabled bit for login keys workaround: %s ",
+		tpg->tpgt, (a->login_keys_workaround) ? "ON" : "OFF");
 
 	return 0;
 }

drivers/target/iscsi/iscsi_target_tpg.h

···
 extern int iscsit_ta_t10_pi(struct iscsi_portal_group *, u32);
 extern int iscsit_ta_fabric_prot_type(struct iscsi_portal_group *, u32);
 extern int iscsit_ta_tpg_enabled_sendtargets(struct iscsi_portal_group *, u32);
+extern int iscsit_ta_login_keys_workaround(struct iscsi_portal_group *, u32);
 
 #endif /* ISCSI_TARGET_TPG_H */

include/target/iscsi/iscsi_target_core.h

···
 #define TA_DEFAULT_FABRIC_PROT_TYPE	0
 /* TPG status needs to be enabled to return sendtargets discovery endpoint info */
 #define TA_DEFAULT_TPG_ENABLED_SENDTARGETS 1
+/*
+ * Used to control the sending of keys with optional to respond state bit,
+ * as a workaround for non RFC compliant initiators,that do not propose,
+ * nor respond to specific keys required for login to complete.
+ *
+ * See iscsi_check_proposer_for_optional_reply() for more details.
+ */
+#define TA_DEFAULT_LOGIN_KEYS_WORKAROUND 1
 
 #define ISCSI_IOV_DATA_BUFFER		5
 
···
 	u8			t10_pi;
 	u32			fabric_prot_type;
 	u32			tpg_enabled_sendtargets;
+	u32			login_keys_workaround;
 	struct iscsi_portal_group *tpg;
 };