We have concerns related to SA usage leakage.  That is, it is possible for application clients to create enough SA's in a device server - with the timeout values long enough - that the device server is out of resources to create another.  While the answer seems obvious - allow the device server to implicitly abandon an SA for vendor-specific reasons, there is no explicit mention of this in SPC-4 that we can find.  If the DS is not allowed to implicitly abandon an SA, the opens up the avenue for Denial of Service attacks - an attacker could use up all the SA resources with maximum timeout values.

Key points being:
A) the DS needs to be able to clear space for a new SA
B) no notification of lost SA should be reported to AC until the AC attempts to use an SA
C) the expected behaviors of the DS and the AC should be explicitly stated in SPC-4 and be general (i.e., not tied to each usage defined (e.g., ESP-SCSI))
D) There should be a unique additional sense code for when an attempt to use an unknown SAI is made

Please provide comments as we will be driving to a proposal to make this happen.

Thanks,

Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt@us.ibm.com
http://www-03.ibm.com/servers/storage/