iscsi-target: Do not reject non-immediate CmdSNs exceeding MaxCmdSN

This patch changes iscsit_sequence_cmd() logic to no longer reject
non-immediate CmdSNs that exceed MaxCmdSN with a protocol error,
but instead silently ignore them.

This is done to correctly follow RFC-3720 Section 3.2.2.1:

   For non-immediate commands, the CmdSN field can take any
   value from ExpCmdSN to MaxCmdSN inclusive.  The target MUST silently
   ignore any non-immediate command outside of this range or non-
   immediate duplicates within the range.

Reported-by: Santosh Kulkarni <santosh.kulkarni@calsoftinc.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/iscsi/iscsi_target_core.h b/drivers/target/iscsi/iscsi_target_core.h
index f2094d2..8dcb3c1 100644 (file)
--- a/drivers/target/iscsi/iscsi_target_core.h
+++ b/drivers/target/iscsi/iscsi_target_core.h
@@ -193,6 +193,7 @@ enum recover_cmdsn_ret_table {
        CMDSN_NORMAL_OPERATION          = 0,
        CMDSN_LOWER_THAN_EXP            = 1,
        CMDSN_HIGHER_THAN_EXP           = 2,
+       CMDSN_MAXCMDSN_OVERRUN          = 3,
 };
 
 /* Used for iscsi_handle_immediate_data() return values */

diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
index 45b8fd1..9064926 100644 (file)
--- a/drivers/target/iscsi/iscsi_target_util.c
+++ b/drivers/target/iscsi/iscsi_target_util.c
@@ -242,9 +242,9 @@ static inline int iscsit_check_received_cmdsn(struct iscsi_session *sess, u32 cm
         */
        if (iscsi_sna_gt(cmdsn, sess->max_cmd_sn)) {
                pr_err("Received CmdSN: 0x%08x is greater than"
-                      " MaxCmdSN: 0x%08x, protocol error.\n", cmdsn,
+                      " MaxCmdSN: 0x%08x, ignoring.\n", cmdsn,
                       sess->max_cmd_sn);
-               ret = CMDSN_ERROR_CANNOT_RECOVER;
+               ret = CMDSN_MAXCMDSN_OVERRUN;
 
        } else if (cmdsn == sess->exp_cmd_sn) {
                sess->exp_cmd_sn++;
@@ -303,14 +303,16 @@ int iscsit_sequence_cmd(struct iscsi_conn *conn, struct iscsi_cmd *cmd,
                ret = CMDSN_HIGHER_THAN_EXP;
                break;
        case CMDSN_LOWER_THAN_EXP:
+       case CMDSN_MAXCMDSN_OVERRUN:
+       default:
                cmd->i_state = ISTATE_REMOVE;
                iscsit_add_cmd_to_immediate_queue(cmd, conn, cmd->i_state);
-               ret = cmdsn_ret;
-               break;
-       default:
-               reason = ISCSI_REASON_PROTOCOL_ERROR;
-               reject = true;
-               ret = cmdsn_ret;
+               /*
+                * Existing callers for iscsit_sequence_cmd() will silently
+                * ignore commands with CMDSN_LOWER_THAN_EXP, so force this
+                * return for CMDSN_MAXCMDSN_OVERRUN as well..
+                */
+               ret = CMDSN_LOWER_THAN_EXP;
                break;
        }
        mutex_unlock(&conn->sess->cmdsn_mutex);