[Bug-tar] Security Question - Unused File Space from a file'sEOF to end of physical block on disk

[Stone, Todd -Systems]

Our system contains both UNCLASSIFIED and CLASSIFIED data.  Our security agency 
(AF-CERT in our case) have procedures for copying from a mixed classification 
system to UNCLASSIFIED media.

Files occupy full blocks and the concern is over contents of the unused (slack) 
space between the files's EOF (End-of-File) marker and physical end of the data 
block as occupied on disk.  This unused data could be considered CLASSIFIED if 
contents aren't zeroed out.  Does or has anyone modified GNU-TAR to clear 
unallocated (slack) space?

Has anyone else been down this road?

R. Todd Stone 
Flight Safety Software Engineer 
SLRSC - Software Engineering 


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