[cifs-protocol] [PFIF] Synchronize bit on NT CreateX does not match what I observe from Windows clients

Steve French smfrench at gmail.com
Tue Mar 3 00:05:02 GMT 2009

On page 50 of MS-SMB the document says the "SYNCHRONIZE" bit in the
DesiredAccess field "SHOULD NOT be used by the sender and MUST be
ignored by the receiver."
but by using the WindowsXP client I see the client setting this bit in
at least some SMB NT CreateX requests (e.g. prior to querying a
security descriptor).

In addition by searching for references mentioning this bit I saw some
things which hint that this bit may need to be set in some cases (e.g.
GENERIC WRITE permission apparently includes this bit, and local
applications which set FILE_SYNCHRONOUS_IO_ALERT in CreateOptions
apparently must set the SYNCHRONIZE bit in DesiredAccess

Last week one server vendor claimed that the SYNCHRONIZE bit in
DesiredAccess has an effect on the semantics of rename and delete open
field (which I have not been able to verify).

Please clarify why and when the SYNCHRONIZE bit should be set.



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