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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Login Proposal
The recent plugfest highlighted areas of the login procedure that could be
improved.
With this in mind, Bob Russell, Marjorie Krueger, and myself have been
working on
a proposal for the Login procedure.
Our goals were to keep it inline as much as possible with 0.7 of the
specification and
to ensure connectivity can be maintained amongst target and initiators. I
believe we
have meet all the goals we set out to do.
I have also attached a Login Reference Model (in the form of c code) which
backs up
our proposal. Please note that the reference model is only a reference
model and should
not be considered as, or be part of the iSCSI specification.
Cheers
Matthew Burbridge
Marjorie Krueger
Bob Russell
++++++++++++++++++++++++
The Login Proposal:
Definitions:
FBit means "I have nothing (more) to negotiate"
Request: The first occurrence of a Text Parameter from the initiator or the
target. A request
MUST be answered with a reply.
Reply: A Text Parameter that is a response to a Request.
Negotiation: A request followed by a response.
1.1 Actions at the Initiator
The initiator starts the login phase by sending a Login Command PDU.
The IIN MUST be present in the login command. The SessionType MUST be
present if the
session type is Discovery, Boot or CopyManager. It MAY be present if
SessionType=Normal.
The ITN MUST be present unless SessionType=Discovery when it is optional.
The initiator
MUST NOT send operational text parameters in the login command. The table
below defines
the parameter present in the login command.
SessionType SessionType IIN ITN
Present in Present in Present in
Login? Login? Login?
Normal Optional Yes Yes
Boot Yes Yes Yes
CopyManager Yes Yes Yes
Discovery Yes Yes Optional
SecurityContextComplete=yes MUST NOT be present in the login command
Operational Parameters MUST NOT be present in the login command
At anytime the initiator MAY terminate the login killing the TCP connection.
If the initiator requires security negotiation it MUST send one or more
security
parameters: (AuthMethod, HeaderDigest, DataDigest) in the login command.
Fbit Security
Parameters Description
Present
0 No Initiator has no security parameters
to negotiate but has operational
parameters
to negotiate.
0 Yes The initiator wants to negotiate
security.
1 No The initiator has no security parameters
to
negotiate and no operational parameters
to
negotiate.
1 Yes ILLEGAL. Target must reject login
(Login Status = 0200)
1.2 Actions at the Target
On receipt of the Login Command the target MUST respond according to the
rules below:
If the InitiatorName is not present the target MUST reject the login
by sending a Login Response with FBit=1 and StatusCode=0200. Similary, if
the
SessionType is not Discovery and the TargetName is not present the target
MUST
reject the login by sending a Login Response with FBit=1 and
StatusCode=0200. It
both cases the target should kill the TCP connection after the login
response has
successfully been sent.
At anytime the target MAY terminate the login by sending a login response
with
the FBit set to 1 and a non-zero StatusCode. The target should kill the TCP
connection after the login response has successfully been sent.
If the login command contains security parameters, the target MUST enter the
security
phase of the login. It MUST send response to those security parameters and
MAY start
negotiating security parameters if the parameters that it wants to negotiate
are not
in the Login command. The target responses with a Text Response (F=0).
If the login command does not contain security parameters the target MUST
perform one
of the two actions below:
a) If the target requires security negotiation to be performed, then
it MUST
enter the security phase and MUST send a text response containing
one or
more security parameters and F=0.
b) If the target does not require security negotiation (and therefore
neither
does the initiator) it MUST perform one of the actions defined by
the table
below.
Initiator Target has Action
FBit params to
negotiate
0 No Send Text Response with F=1
(Initiator
only wants to negotiate operational
parameters).
0 Yes Send Text Response with operation
params
If all parameters can be sent in
a single response then F=1 else F=0
(Both target and initiator want to
negotiate operational parameters).
1 No Send Login Response with F=1.
(Neither target
nor initiator want to negotiate
operational
parameters).
1 Yes Send Text Response. If all
parameters can be
sent in a single response then F=1
else
F=0 (Target only wants to negotiate
operational parameters).
1.3 General Rules
If an initiator or target has text parameters (security or operational) to
negotiate
then it MUST send them at the earliest opportunity and it MUST NOT send an
empty text
command.
An initiator or target MUST respond to the a text parameter request with a
text parameter
response in the next text PDU to be sent.
Once an initiator or target has completed initiating negotiations (security
or operational)
it MUST not initiate any more of the same type (security or operational).
In other
words it can not go backwards.
Operational Parameters MUST NOT be negotiated during the security phase.
Security Parameters MUST NOT be negotiated during the operartional phase.
When a party has no more text parameters to negotiate then the FBit MUST
be set in the PDU containing the last text parameter request and all
subsequent
PDUs. For example: if an initiator only wants to negotiate "InitialR2T=yes"
and no others, then it MUST set the FBit to 1 in the commands containing
"InitialR2T=yes".
Once the FBit has been set to 1, it MUST not be set back to 0. Also, if
the FBit is 1 then the party MUST not instigate anymore text parameter
negotiations. It can only respond to requests from the other party.
If FMarker=yes then SFMarkInt and RFMarkInt MUST be present in the same
Text PDU as FMarker=yes. If FMarker=no then SHOULD NOT be present. If they
are then the remote party MUST reply to them and echo the values sent in the
initial PDU.
1.4 Completion of Security Phase
[Authors note: This section has been extracted from v0.7 but I have made
some
clarifications to the version 0.7 spec. - Changes in CAPITALS]
-Every party in the security negotiation MUST [Added MUST]
indicate that it has completed building its security context
(has all the required information) by sending the key=value pair:
SecurityContextComplete=yes
The other party either offers some more SECURITY parameters or
answers
with the same:
SecurityContextComplete=yes
The party that is ready MUST [Added MUST] keep sending the
SecurityContextComplete=yes pair (in addition to new security
Parameter REPLYS if required) until the handshake is complete.
Once the party has set SecurityContextComplete=yes it MUST
not instigate anymore negotiations but it MUST respond to any
requests from the other pary.
If the initiator has been the last to complete the SECUIRTY PHASE
it
MUST NOT start sending operational parameters within the same
text command; a text response including only
SecurityContextComplete=yes concludes the security sub-phase.
If the target has been the last to complete the SECURITY PHASE,
the
initiator can start the operational parameter negotiation with
the next text command; the security negotiation sub-phase ends
with the target text response.
The SecurityContextComplete handshake MUST be performed if any
of negotiating parties has offered a security/integrity item
(even if it is not selected).
All PDUs sent after the security negotiation sub phase MUST be
built using the agreed security.
This proposal removes from 0.7 of the spec:
Partial Login response: It no longer coveys any information.
OpParamReset: No longer required as operational parameters can not be
negotiated
during security phase.
Keep:
SecurityContextComplete=yes. This is how 0.7 works. If people disagree
then
we can vote and change it.
Matthew Burbridge
Senior Development Engineer
NIS-Bristol
Hewlett Packard
Telnet: 312 7010
E-mail: matthewb@bri.hp.com
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