Compression filter named in a backup header is executed in restore
environment (commonly dom0). While this field is properly authenticated,
there may be cases where backup archive comes from less
trusted source, like migrating from potentially compromised
system.
Modify backup header parsing code to add field specific validators.
Whitelist only know crypto, hmac and compression algorithms.
Based on a patch by Jean-Philippe Ouellet <jpo@vt.edu>
Reported-by: Jean-Philippe Ouellet <jpo@vt.edu>
10f15e6669