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    iSCSI: Login State Tables



    
    Julian and interested parties:
    
    The login mechanisms as documented in 06 concerns me, as there is a lot of
    room for
    "interpretation" of the current text. I have attempted to pull the 06
    statements together
    into a state table in order to avoid what I fear may be a bunch of
    interoperability
    headaches. The state table, however, also places some restrictions on the
    process that
    is not in the current text. In particular:
    
    1. It forces all negotiations to go through an explicit security handshake.
    If
    security is not being used the handshake still takes place. This allows a
    target to
    demand security in a clean manner even if the initiator did not request it.
    2. It explicitly places most parameters into an operation class and a
    security class.
    These parameters may only be exchanged during defined phases of the login
    process.
    (This is intended to remove ambiguity associated with the use of operational
    parameters
    that were negotiated in the security phase). There is a set of parameters
    that are
    really not in either camp. These parameters can be used in both the security
    phase and
    the operational phase. Once negotiated their values would remain established
    unless
    explicitly renegotiated. [Note: Another choice here is to place all
    operational parameters
    into this category and apply the rule that all negotiated values MUST be
    maintained by
    both parties unless renegotiated.]
    3. It does not allow a target to respond to a Text PDU that has a F=1
    setting with new
    key=value pairs in a login PDU with F=1.
    4. It allows the initiator to continue negotiations if it was happy with a
    context but
    additional negotiations made it unhappy. This allows the protocol to address
    situations
    in which there is a coupling between parameters.
    
    This is intended to mostly be a clarification of what I think 06 is
    attempting to
    state, however, you may think differently. If there is basic agreement that
    this is
    what we are trying to do in 06 I would like to see something of this nature
    added to
    the draft.
    
    
    
    Parameter classification:
    
    Operational Parameters:
    Maxconnections, FMarker, RFMarker, RFMarkInt, SFMarkInt, IFMarkInt,
    InitialR2T,
    BidiInitialR2T, ImmediateData, DataPDULength, FirstBurstSize,
    LogoutLoginMinTime,
    LogoutLoginMaxTime, EnableACA, MaxOutstandingR2T, DataOrder, BootSession,
    Glen-Turner Vendor Specific Keys.
    
    Not Classified - TargetName, InitiatorName, TargetAlias, InitiatorAlias,
    TargetAddress, SendTargets
    
    Security - DataDigest, HeaderDigest, AuthMethod
    
    
    
    Identifiers used in login state table
    
    SecDone - An indicator that takes on the value True (T) or False (F).
              This indicator is when the local device is satisfied with
              the current security context and is ready to move to the
              operational parameter negotiation phase. When a PDU has
              been received the value of SecDone is that established
              after the contents of the received PDU have been evaluated.
    OpDone -  This is the logical equivalent of SecDone for the Operational
    Phase.
    Fsent -   This variable is used to indicate that the last PDU sent by
              this device had the F bit set to 1. [Note: The meaning of the
              F bit is changed by this usage. It no longer means that this is
              the last PDU to be sent by the initiator, in this context it means
              that this is the last text PDU I will send if the target
              doesn't continue the negotiation.]
    SCC -	  A short hand notation for the key "SecurityContextComplete"
    Rcv_Text- A valid Text PDU was received
    Rcv_Login-A login PDU was received
    Xmit_Text-A Text PDU is transmitted
    Perror -  A protocol error was detected
    
    Initiator Login State Transition Table:
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |C State | Event(s) and conditions |N State |         Actions         |
    Notes |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |START   |(TCP connection Est-     |SEC-END |xmit login(SCC=yes)      |  1
    |
    |        |ablished) & SecDone      |        |                         |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |START   |(TCP connection Est-     |SEC-NEG |xmit login               |
    |
    |        |ablished & not(SecDone)  |        |                         |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SEC-NEG |Rcv_Text & SecDone=F     |SEC-NEG |Xmit_Text                |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SEC-NEG |Rcv_Text & SecDone=T     |SEC-END |xmit_Text(SCC=yes)       |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SEC-NEG |Perror                   |ABORT   |TCP connection terminated|  2
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SEC-END |Rcv_Text & SecDone=F     |SEC-NEG |xmit_Text                |  3
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SEC-END |Rcv_Text & SecDone=T     |SEC-NEG |xmit_Text                |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SEC-END |Rcv_Text(SCC=yes) &      |OPER-NEG|xmit_Text                |  4
    |
    |        |SecDone = T & OpDone = F |        |                         |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SEC-END |Rcv_Text(SCC=yes) &      |OPER-END|xmit_Text                |  4
    |
    |        |SecDone = T & OpDone = T |        |                         |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SEC-END |Perror                   |ABORT   |TCP connection terminated|  5
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER-NEG|Rcv_Text & OpDone = F    |OPER-NEG|xmit_Text                |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER-NEG|Rcv_Text & OpDone = T    |OPER-END|xmit_Text(F=1), Fsent=1  |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER-NEG|Perror                   |ABORT   |TCP connection terminated|  6
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER-END|Rcv_Text & OpDone = F    |OPER-NEG|xmit_Text, Fsent=0       |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER-END|Rcv_Text & OpDone = T    |OPER-END|xmit_Text(F=1), Fsent=1  |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER-END|Rcv_Login(F=1) & Fsent=1 |FULL    |                         |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER-END|Perror                   |ABORT   |TCP connection terminated|  7
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    
    Notes:
    All - The F bit is set to zero (F=0) unless otherwise indicated
          in the login state table.
    All - Operational parameter key=value lists SHALL NOT be allowed
          before the security context has been completed.
    All - The Key=value pair "SecurityContextComplete=yes" must always
          be sent by itself
    1   - No key=value pairs may be included in this PDU
          except "SecurityContextComplete=yes"
    2   - Identified protocol errors are: Rcv_Text has F=1, Rcv_Text
          has operational parameters
    3   - If the target sends a security parameter that causes the initiator
          to no longer be satisfied with the current security context the
    initiator
          continues the security negotiations.
    4   - This and subsequent PDUs sent on this connection SHALL be transmitted
          using the negotiated security context.
    5   - Identified protocol errors are Rcv_Text has F=1, Rcv_Text has
          operational parameters
    6   - Identified protocol errors are: Rcv_Text has F=1 and Fsent is not set,
          Rcv_Text contains a security key
    7   - Identified protocol errors are: Rcv_Text has F=1, A login PDU is
          received with new key=value parameters, A login PDU is received with
    F=0.
    
    
    Target Login State Transition Table:
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |C State | Event(s) and conditions |N State |         Actions         |
    Notes |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |WAIT    |rcv_login(scc=yes) &     |OPER    |xmit_Text(scc=yes)       |  1
    |
    |        |SecDone = T              |        |                         |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |WAIT    |rcv_login & SecDone = T  |SECURITY|xmit_Text(scc=yes)       |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |WAIT    |rcv_login(scc=yes) &     |SECURITY|xmit_Text                |
    |
    |        |SecDone = F              |        |                         |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |WAIT    |rcv_login & SecDone = T  |SECURITY|xmit_Text                |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |WAIT    |Perror                   |ABORT   |xmit_Login(F=1)          |  2
    |
    |        |                         |        |status_class != 0        |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SECURITY|rec_Text & SecDone = F   |SECURITY| xmit_Text               |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SECURITY|rec_Text & SecDone = T   |SECURITY| xmit_Text(scc=yes)      |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SECURITY|rec_text(Scc=yes) &      |SECURITY| xmit_Text               |
    |
    |        | SecDone = F             |        |                         |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SECURITY|rec_text(Scc=yes) &      |OPER    | xmit_Text(SCC=yes)      |  3
    |
    |        | SecDone = T             |        |                         |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |SECURITY|Perror                   |ABORT   |xmit_Login(F=1)          |  4
    |
    |        |                         |        |status_class != 0        |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER    |rcv_Text & OpDone = F    |OPER    |xmit_Text                |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER    |rcv_Text & OpDone = T    |OPER    |xmit_Text                |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER    |rcv_Text(F=1)            |OPER    |xmit_Text                |
    |
    |        |OpDone = F               |        |                         |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER    |rcv_Text(F=1)            |Full    |xmit_Login(F=1)          |  5
    |
    |        |OpDone = T               |        |                         |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    |OPER    |Perror                   |ABORT   |xmit_Login(F=1)          |  6
    |
    |        |                         |        |status_class != 0        |
    |
    +--------+-------------------------+--------+-------------------------+-----
    --+
    
    
    1. The Target SHALL NOT send a login PDU back unless there is an error and
    it
       is ending the login process. The next PDU to be received will be using
    the
       negotiated security context (externally established or default)
    2. Identified protocol errors: The F bit is set in the login PDU,
    Operational
       parameters are given as key=value lists in the PDU
    3. The device SHALL use the negotiated security on the all subsequent PDUs
       received for this connection.
    4. Identified protocol errors: The F bit is set in the text PDU, a login PDU
       was received, operational parameters were received in the PDU.
    5. The target SHALL NOT send any additional key=value lists in this PDU.
    6. Identified protocol errors: Security parameters were received in the PDU.
    
    
    Barry Reinhold
    Principal Architect
    Trebia Networks
    barry.reinhold@trebia.com
    603-868-5144/603-659-0885/978-929-0830 x138
    
    


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Last updated: Tue Sep 04 01:04:39 2001
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